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Human immunoglobulin G (IgG) exists as four subclasses IgG1-4, each of which has two Fab subunits joined by two hinges to a Fc subunit. IgG4 has the shortest hinge with 12 residues. The Fc subunit has two glycan chains, but the importance of glycosylation is not fully understood in IgG4. Here, to evaluate the stability and structure of non-glycosylated IgG4, we performed a multidisciplinary structural study of glycosylated and deglycosylated human IgG4 A33 for comparison with our similar study of human IgG1 A33. After deglycosylation, IgG4 was found to be monomeric by analytical ultracentrifugation; its sedimentation coefficient of 6.52 S was reduced by 0.27 S in reflection of its lower mass. X-ray and neutron solution scattering showed that the overall Guinier radius of gyration RG and its cross-sectional values after deglycosylation were almost unchanged. In the P(r) distance distribution curves, the two M1 and M2 peaks that monitor the two most common distances within IgG4 were unchanged following deglycosylation. Further insight from Monte Carlo simulations for glycosylated and deglycosylated IgG4 came from 111,382 and 117,135 possible structures respectively. Their comparison to the X-ray and neutron scattering curves identified several hundred best-fit models for both forms of IgG4. Principal component analyses showed that glycosylated and deglycosylated IgG4 exhibited different conformations from each other. Within the constraint of unchanged RG and M1-M2 values, the glycosylated IgG4 models showed more restricted Fc conformations compared to deglycosylated IgG4, but no other changes. Kratky plots supported this interpretation of greater disorder upon deglycosylation, also observed in IgG1. Overall, these more variable Fc conformations may demonstrate a generalisable impact of deglycosylation on Fc structures, but with no large conformational changes in IgG4 unlike those seen in IgG1. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to examine how and why individuals involved in executive remuneration (top pay) decision-making consider quantum as being appropriate rather than excessive, theorised under the rubric of accountability. Design/methodology/approach: In-depth interviews were conducted with non-executive directors (NEDs) serving on remuneration committees (Remcos), institutional investors, their external advisers and internal HR reward experts. Transcripts were analysed using NVivo and the Gioia qualitative methodology. Findings: Defining, measuring and applying performance conditionality in the determination of top pay quantum such that it aligns with company strategy/culture and values, as well as individual recipient motivations, is difficult. While creative approaches to setting top pay so as to attract, retain and motivate key personnel are welcomed, these risk Remco members' personal/organisational reputations. Members recognise disconnection between top pay quantum and general pay levels and how the media highlights social inequality leading to public distrust. They believe they can contribute to more socially acceptable quantum by applying their own values in top pay decision-making. Originality/value: Sanctions-based, trust-based and selection/peer networks/felt-based accountability theory is used to explain decision-makers' actions when determining top pay quantum. This paper extends felt accountability theory to encompass public/societal accountability in the context of the appropriateness of top pay quantum decisions. [ABSTRACT FROM AUTHOR]

FcγRI (CD64) is the only high-affinity Fcγ receptor found on monocytes, macrophages, eosinophils, neutrophils and dendritic cells. It binds immunoglobulin G (IgG) antibody-antigen complexes at its Fc region to trigger key immune responses. CD64 contains three immunoglobulin-fold extracellular domains (D1, D2 and D3) and a membrane-spanning region. Despite the importance of CD64, no solution structure for this is known to date. To investigate this, we used analytical ultracentrifugation, small-angle X-ray scattering, and atomistic modelling. Analytical ultracentrifugation revealed that CD64 was monomeric with a sedimentation coefficient s020,w of 2.53 S, together with some dimer. Small-angle X-ray scattering showed that its radius of gyration RG was 3.3–3.4 nm and increased at higher concentrations to indicate low dimerization. Monte Carlo modelling implemented in the SASSIE-web package generated 279,162 physically-realistic trial CD64 structures. From these, the scattering best-fit models at the lowest measured concentrations that minimised dimers revealed that the D1, D2 and D3 domains were structurally similar to those seen in three CD64 crystal structures, but showed previously unreported flexibility between D1, D2 and D3. Despite the limitations of the scattering data, the superimposition of the CD64 solution structures onto crystal structures of the IgG Fc-CD64 complex showed that the CD64 domains do not sterically clash with the IgG Fc region, i.e. the solution structure of CD64 was sufficiently compact to allow IgG to bind to its high-affinity Fcγ receptor. This improved understanding may result in novel approaches to inhibit CD64 function, and opens the way for the solution study of the full-length CD64-IgG complex. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to examine how individuals involved in top pay determination view their role and accountabilities, and capability development needs, theorised under the rubric of professionalisation. Design/methodology/approach: A qualitative research approach draws upon in-depth interviews with non-executive directors serving on remuneration committees (Remcos), institutional investors, their external advisors, and HR reward experts. Findings: Regulation has addressed remuneration committee resourcing implications but has yet to consider the ramifications for implied professionalisation requirements for the independent actors involved. Non-executives' and institutional investors' professional engagement is potentially hindered by the capability and capacity required for the activities involved and, for NEDs, the reward attached. Research limitations/implications: Further research is needed to evaluate professionalisation initiatives by top pay regulators and assess their impact on executive remuneration in practice. Practical implications: Thorough induction, tailored training, and continuous professional development are crucial to quality executive remuneration decision-taking; organisational and regulatory attention to these issues is required along with widening NED selection and recognition criteria. Originality/value: This paper provides new knowledge on how top pay decision-takers view their role, the competencies required, and necessary professional development needed to achieve organisational competitive advantage. It reveals a potential dark side to top pay decision-taker professionalisation if individuals repurpose themselves as occupants of part-time executive roles undermining corporate executives. [ABSTRACT FROM AUTHOR]

ZAG is a multifunctional glycoprotein with a class I MHC‐like protein fold and an α1‐α2 lipid‐binding groove. The intrinsic ZAG ligand is unknown. Our previous studies showed that ZAG binds the dansylated C11 fatty acid, DAUDA, differently to the boron dipyrromethane C16 fatty acid, C16‐BODIPY. Here, the molecular basis for this difference was elucidated. Multi‐wavelength analytical ultracentrifugation confirmed that DAUDA and C16‐BODIPY individually bind to ZAG and compete for the same binding site. Molecular docking of lipid‐binding in the structurally related Cluster of differentiation 1 proteins predicted nine conserved ligand contact residues in ZAG. Twelve mutants were accordingly created by alanine scanning site directed mutagenesis for characterisation. Mutation of Y12 caused ZAG to misfold. Mutation of K147, R157 and A158 abrogated C16‐BODIPY but not DAUDA binding. L69 and T169 increased the fluorescence emission intensity of C16‐BODIPY but not of DAUDA compared to wild‐type ZAG and showed that C16‐BODIPY binds close to T169 and L69. Distance measurements of the crystal structure revealed K147 forms a salt bridge with D83. A range of bioactive bulky lipids including phospholipids and sphingolipids displaced DAUDA from the ZAG binding site but unexpectedly did not displace C16‐BODIPY. We conclude that the ZAG α1‐α2 groove contains separate but overlapping sites for DAUDA and C16‐BODIPY and is involved in binding to a bulkier and wider repertoire of lipids than previously reported. This work suggested that the in vivo activity of ZAG may be dictated by its lipid ligand. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to report on trends in the deployment of minority expatriates, review organisational interventions to increase expatriate diversity and to consider the challenges facing employers in widening expatriate diversity through a review of practitioner publications published by relocation management companies/consultancies. Design/methodology/approach: A review of 109 practitioner publications on organisational international assignment policy and practice was conducted to identify trends across three decades in minority expatriation and employer interventions to widen expatriate diversity. Findings: Practitioner publications record percentage female expatriate participation and expatriate age profiles. While expatriate diversity challenges are reported, employer interventions focus on supporting women and LGBTQ+ assignees but with little detail on their outcomes. There is little emphasis on ethnicity/race, religion, disability, pregnancy/maternity, intersectionality of diversity characteristics and inclusion. Research limitations/implications: Practitioner publications consulted were primarily Western-focused, with access to a "complete" publications record precluded. Academic research that compares employer policy on diversity interventions with how it is implemented is needed. Practical implications: A stronger focus on supporting the full range of expatriate diversity attributes and intersectionality is required, explaining how challenges have been addressed and inclusion achieved. Social implications: Analysis of employer interventions could assist organisations to widen expatriate diversity and inclusion, and minorities to access international careers. Originality/value: This review of practitioner data reveals trends in the deployment of minority expatriates, interventions taken by employers and challenges they perceive in widening expatriate diversity, providing a unique perspective and enriching our understanding of academic expatriate diversity research. Path-dependent organisational action may hinder employers' future focus on diversity, inclusion and intersectionality. [ABSTRACT FROM AUTHOR]

Complement Factor H (CFH), with 20 short complement regulator (SCR) domains, regulates the alternative pathway of complement in part through the interaction of its C-terminal SCR-19 and SCR-20 domains with host cell-bound C3b and anionic oligosaccharides. In solution, CFH forms small amounts of oligomers, with one of its self-association sites being in the SCR-16/20 domains. In order to correlate CFH function with dimer formation and the occurrence of rare disease-associated variants in SCR-16/20, we identified the dimerization site in SCR-16/20. For this, we expressed, in Pichia pastoris , the five domains in SCR-16/20 and six fragments of this with one-three domains (SCR-19/20, SCR-18/20, SCR-17/18, SCR-16/18, SCR-17 and SCR-18). Size-exclusion chromatography suggested that SCR dimer formation occurred in several fragments. Dimer formation was clarified using analytical ultracentrifugation, where quantitative c(s) size distribution analyses showed that SCR-19/20 was monomeric, SCR-18/20 was slightly dimeric, SCR-16/20, SCR-16/18 and SCR-18 showed more dimer formation, and SCR-17 and SCR-17/18 were primarily dimeric with dissociation constants of ~5 µM. The combination of these results located the SCR-16/20 dimerization site at SCR-17 and SCR-18. X-ray solution scattering experiments and molecular modelling fits confirmed the dimer site to be at SCR-17/18, this dimer being a side-by-side association of the two domains. We propose that the self-association of CFH at SCR-17/18 enables higher concentrations of CFH to be achieved when SCR-19/20 are bound to host cell surfaces in order to protect these better during inflammation. Dimer formation at SCR-17/18 clarified the association of genetic variants throughout SCR-16/20 with renal disease. [ABSTRACT FROM AUTHOR]

Hereditary blood coagulation factor VII (FVII) deficiency is a rare autosomal recessive bleeding disorder resulting from variants in the gene encoding FVII (F7). Integration of genetic variation with functional consequences on protein function is essential for the interpretation of the pathogenicity of novel variants. Here, we describe the integration of previous locus‐specific databases for F7 into a single curated database with enhanced features. The database provides access to in silico analyses that may be useful in the prediction of variant pathogenicity as well as cross‐species sequence alignments, structural information, and functional and clinical severity described for each variant, where appropriate. The variant data is shared with the F7 Leiden Open Variation Database. The updated database now includes 221 unique variants, representing gene variants identified in 728 individuals. Single nucleotide variants are the most common type (88%) with missense representing 74% of these variants. A number of variants are found with relatively high minor allele frequencies that are not pathogenic but contribute significantly to the likely pathogenicity of coinherited variants due to their effect on FVII plasma levels. This comprehensive collection of curated information significantly aids the assessment of pathogenicity. [ABSTRACT FROM AUTHOR]

Introduction: Advances in genomic sequencing have facilitated the sequencing of genes associated with disorders of haemostasis. The identification of variants within genes and access to curated data incorporating structural, functional, evolutionary as well as phenotypic data has become increasingly important in order to ascribe pathogenicity. Aim: The European Association for Haemophilia and Allied Disorders (EAHAD) Coagulation Factor Variant Database Project aims to provide a single port of entry to a web‐accessible resource for variants in genes involved in clinical bleeding disorders. Results: New databases have evolved from previously developed single gene variant coagulation database projects, incorporating new data, new analysis tools and a new common database architecture with new interfaces and filters. These new databases currently present information about the genotype, phenotype (laboratory and clinical) and structural and functional effects of variants described in the genes of factor (F) VII (F7), FVIII (F8), FIX (F9) and von Willebrand factor (VWF). Conclusion: The project has improved the quality and quantity of information available to the haemostasis research and clinical communities, thereby enabling accurate classification of disease severity in order to make assessments of likely pathogenicity. [ABSTRACT FROM AUTHOR]

Human zinc-α2-glycoprotein (ZAG) is a 42 kDa adipokine which regulates body fat mass and is associated with cachexia and obesity. ZAG belongs to the major histocompatibility complex class I protein family and binds long-chain polyunsaturated fatty acids in its groove formed from the α1 and α2 domains. To identify the molecular basis of its lipidbinding function, we determined the first crystal structure at 2.49 Å resolution for fatty acid-bound ZAG, where the ligand was the fluorescent 11-(dansylamino)undecanoic acid (DAUDA). The 192 kDa crystallographic asymmetric unit contained six ZAG and eight fatty acid molecules in unique conformations. Six fatty acid molecules were localised to the ZAG grooves, where their tails were bound in two distinct conformations. The carboxylate groups of three fatty acids projected out of the groove, while the fourth was hydrogen bonded with R73 inside the groove. Other ligand-residue contacts were primarily hydrophobic. A new fatty acid site was revealed for two further DAUDA molecules at the ZAG a3 domains. Following conformational changes from unbound ZAG, the α3 domains formed tetrameric β-barrel structures lined by fatty acid molecules that doubled the binding capacity of ZAG. Analytical ultracentrifugation revealed that ZAG in solution was a monomer in the absence of DAUDA, but formed small amounts of tetramers with DAUDA. By showing that ZAG binds fatty acids in different locations, we demonstrate an augmented mechanism for fatty acid binding in ZAG that is distinct from other known fatty acid binding proteins, and may be relevant to cachexia. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to examine the role of organisational performance and development review policy and practice on women's access to international careers via long-term expatriate assignments in the oil and gas industry, with a specific focus on women's perceptions of procedural justice.Design/methodology/approach A qualitative cross-sectional case study research design is used to analyse performance and development review, and international assignment policies in two firms, together with in-depth, semi-structured interviews with 14 Human Resource policy custodians and 21 female long-term current assignees.Findings Women assignees do not see performance and development reviews as effective mechanisms to access expatriate roles. Nonetheless, women use these procedures while also operating within senior male networks to signal their desire to expatriate.Research limitations/implications This study identifies differences between organisational policy objectives and policy implementation, and female assignees' experiences and expectations of accessing expatriate roles. Women's perceptions of organisational justice are not harmed because women place more emphasis on process and conversations than on policy. Research propositions are suggested extending organisational justice theory.Practical implications Clear articulation of performance and development review processes aids organisational succession planning. Formalised, transparent expatriate career management supports women's access to expatriation. The roles of key personnel in determining access to expatriate career paths require clarification.Originality/value This paper extends our knowledge of women's organisationally assigned expatriate careers and perceptions of procedural justice. Women use performance and development reviews to access expatriate opportunities. Employer action aligned to policy intent could help increase female expatriate participation. [ABSTRACT FROM AUTHOR]

Collagen adopts a characteristic supercoiled triple helical conformation which requires a repeating (Xaa-Yaa-Gly)n sequence. Despite the abundance of collagen, a combined experimental and atomistic modelling approach has not so far quantitated the degree of flexibility seen experimentally in the solution structures of collagen triple helices. To address this question, we report an experimental study on the flexibility of varying lengths of collagen triple helical peptides, composed of six, eight, ten and twelve repeats of the most stable Pro-Hyp-Gly (POG) units. In addition, one unblocked peptide, (POG)10unblocked, was compared with the blocked (POG)10 as a control for the significance of end effects. Complementary analytical ultracentrifugation and synchrotron small angle X-ray scattering data showed that the conformations of the longer triple helical peptides were not well explained by a linear structure derived from crystallography. To interpret these data, molecular dynamics simulations were used to generate 50 000 physically realistic collagen structures for each of the helices. These structures were fitted against their respective scattering data to reveal the best fitting structures from this large ensemble of possible helix structures. This curve fitting confirmed a small degree of non-linearity to exist in these best fit triple helices, with the degree of bending approximated as 4-17° from linearity. Our results open the way for further studies of other collagen triple helices with different sequences and stabilities in order to clarify the role of molecular rigidity and flexibility in collagen extracellular and immune function and disease. [ABSTRACT FROM AUTHOR]

During the activation of complement C4 to C4b, the exposure of its thioester domain (TED) is crucial for the attachment of C4b to activator surfaces. In the C4b crystal structure, TED forms an Arg104-Glu1032 salt bridge to tether its neighbouring macroglobulin (MG1) domain. Here, we examined the C4b domain structure to test whether this salt bridge affects its conformation. Dual polarisation interferometry of C4b immobilised at a sensor surface showed that the maximum thickness of C4b increased by 0.46 nm with an increase in NaCl concentration from 50 to 175 mM NaCl. Analytical ultracentrifugation showed that the sedimentation coefficient s20,w of monomeric C4b of 8.41 S in 50 mM NaCl buffer decreased to 7.98 S in 137 mM NaCl buffer, indicating that C4b became more extended. Small angle X-ray scattering reported similar RG values of 4.89-4.90 nm for C4b in 137-250 mM NaCl. Atomistic scattering modelling of the C4b conformation showed that TED and the MG1 domain were separated by 4.7 nm in 137-250 mM NaCl and this is greater than that of 4.0 nm in the C4b crystal structure. Our data reveal that in low NaCl concentrations, both at surfaces and in solution, C4b forms compact TED-MG1 structures. In solution, physiologically relevant NaCl concentrations lead to the separation of the TED and MG1 domain, making C4b less capable of binding to its complement regulators. These conformational changes are similar to those seen previously for complement C3b, confirming the importance of this salt bridge for regulating both C4b and C3b. [ABSTRACT FROM AUTHOR]

The capabilities of current computer simulations provide a unique opportunity to model small-angle scattering (SAS) data at the atomistic level, and to include other structural constraints ranging from molecular and atomistic energetics to crystallography, electron microscopy and NMR. This extends the capabilities of solution scattering and provides deeper insights into the physics and chemistry of the systems studied. Realizing this potential, however, requires integrating the experimental data with a new generation of modelling software. To achieve this, the CCP-SAS collaboration () is developing open-source, high-throughput and user-friendly software for the atomistic and coarse-grained molecular modelling of scattering data. Robust state-of-the-art molecular simulation engines and molecular dynamics and Monte Carlo force fields provide constraints to the solution structure inferred from the small-angle scattering data, which incorporates the known physical chemistry of the system. The implementation of this software suite involves a tiered approach in which GenApp provides the deployment infrastructure for running applications on both standard and high-performance computing hardware, and SASSIE provides a workflow framework into which modules can be plugged to prepare structures, carry out simulations, calculate theoretical scattering data and compare results with experimental data. GenApp produces the accessible web-based front end termed SASSIE-web, and GenApp and SASSIE also make community SAS codes available. Applications are illustrated by case studies: (i) inter-domain flexibility in two- to six-domain proteins as exemplified by HIV-1 Gag, MASP and ubiquitin; (ii) the hinge conformation in human IgG2 and IgA1 antibodies; (iii) the complex formed between a hexameric protein Hfq and mRNA; and (iv) synthetic `bottlebrush' polymers. [ABSTRACT FROM AUTHOR]

Zinc α2 glycoprotein (ZAG) is an adipokine with a class I MHC protein fold and is associated with obesity and diabetes. Although its intrinsic ligand remains unknown, ZAG binds the dansylated C11 fatty acid 11-(dansylamino)undecanoic acid (DAUDA) in the groove between the α1 and α2 domains. The surface of ZAG has approximately 15 weak zinc-binding sites deemed responsible for precipitation from human plasma. In the present study the functional significance of these metal sites was investigated. Analytical ultracentrifugation (AUC) and CD showed that zinc, but not other divalent metals, causes ZAG to oligomerize in solution. Thus ZAG dimers and trimers were observed in the presence of 1 and 2 mM zinc. Molecular modelling of Xray scattering curves and sedimentation coefficients indicated a progressive stacking of ZAG monomers, suggesting that the ZAG groove may be occluded in these. Using fluorescencedetected sedimentation velocity, these ZAG-zinc oligomers were again observed in the presence of the fluorescent boron dipyrromethene fatty acid C16-BODIPY (4,4-difluoro-5,7- dimethyl-4-bora-3a,4a-diaza-s-indacene-3-hexadecanoic acid). Fluorescence spectroscopy confirmed that ZAG binds C16- BODIPY. ZAG binding to C16-BODIPY, but not to DAUDA, was reduced by increased zinc concentrations. We conclude that the lipid-binding groove in ZAG contains at least two distinct fatty acid-binding sites for DAUDA and C16-BODIPY, similar to the multiple lipid binding seen in the structurally related immune protein CD1c. In addition, because high concentrations of zinc occur in the pancreas, the perturbation of these multiple lipid-binding sites by zinc may be significant in Type 2 diabetes where dysregulation of ZAG and zinc homoeostasis occurs. [ABSTRACT FROM AUTHOR]

Native IgA1, for which no crystal structure is known, contains an O-galactosylated 23-residue hinge region that joins its Fab and Fc regions. IgA nephropathy (IgAN) is a leading cause of chronic kidney disease in developed countries. Because IgA1 in IgAN often has a poorly O-galactosylated hinge region, the solution structures of monomeric IgA1 from a healthy subject and three IgAN patients with four different O-galactosylation levels were studied. Analytical ultracentrifugation showed that all four IgA1 samples were monomeric with similar sedimentation coefficients, s0 20,w. X-ray scattering showed that the radius of gyration (Rg) slightly increased with IgA1 concentration, indicating self-association, although their distance distribution curves, P(r), were unchanged with concentration. Neutron scattering indicated similar Rg values and P(r) curves, although IgA1 showed a propensity to aggregate in heavy water buffer. A new atomistic modelling procedure based on comparisons with 177000 conformationally-randomized IgA1 structures with the individual experimental scattering curves revealed similar extended Y-shaped solution structures for all four differentiallyglycosylated IgA1 molecules. The final models indicated that the N-glycans at Asn263 were folded back against the Fc surface, the C-terminal tailpiece conformations were undefined and hinge O-galactosylation had little effect on the solution structure. The solution structures for full-length IgA1 showed extended hinges and the Fab and Fc regions were positioned asymmetrically to provide ample space for the functionally-important binding of two FcaR receptors to its Fc region. Whereas no link between O-galactosylation and the IgA1 solution structure was detected, an increase in IgA1 aggregation with reduced O-galactosylation may relate to IgAN. [ABSTRACT FROM AUTHOR]

Small-angle X-ray and neutron scattering techniques characterize proteins in solution and complement high-resolution structural studies. They are of particular utility when large proteins cannot be crystallized or when the structure is altered by solution conditions. Atomistic models of the averaged structure can be generated through constrained modelling, a technique in which known domain or subunit structures are combined with linker models to produce candidate global conformations. By randomizing the configuration adopted by the different elements of the model, thousands of candidate structures are produced. Next, theoretical scattering curves are generated for each model for trial-and-error fits to the experimental data. From these, a small family of best-fit models is identified. In order to facilitate both the computation of theoretical scattering curves from atomistic models and their comparison with experiment, the SCT suite of tools was developed. SCT also includes programs that provide sequence-based estimates of protein volume (either incorporating hydration or not) and add a hydration layer to models for X-ray scattering modelling. The original SCT software, written in Fortran, resulted in the first atomistic scattering structures to be deposited in the Protein Data Bank, and 77 structures for antibodies, complement proteins and anionic oligosaccharides were determined between 1998 and 2014. For the first time, this software is publicly available, alongside an easier-to-use reimplementation of the same algorithms in Python. Both versions of SCT have been released as open-source software under the Apache 2 license and are available for download from . [ABSTRACT FROM AUTHOR]

Companies are managing more diverse work forces, and pay systems must be designed to attract, retain and motivate employees who may have very different pay preferences from employees of even a decade ago. This study examines how employee characteristics (i.e., gender, age, education, work experience, annual pay and number of dependents) are related to pay preferences. We found that older respondents with more education and more dependents had a stronger preference for variable pay than did respondents who were younger, less educated and had fewer dependents. Older respondents and those with higher pay preferred less pay transparency than did younger and lower paid respondents. Pay differences based on capability were preferred by better educated employees. When controlling for the other demographic characteristic, we found significant differences among nationalities for all four measures of pay preferences, that is, pay differences, pay variability, bonus plans and pay transparency. [ABSTRACT FROM AUTHOR]

Blood coagulation occurs through a cascade of enzymes and cofactors that produces a fibrin clot, while otherwise maintaining hemostasis. The 11 human coagulation factors (FG, FII–FXIII) have been identified across all vertebrates, suggesting that they emerged with the first vertebrates around 500 Ma. Human FVIII, FIX, and FXI are associated with thousands of disease-causing mutations. Here, we evaluated the strength of selective pressures on the 14 genes coding for the 11 factors during vertebrate evolution, and compared these with human mutations in FVIII, FIX, and FXI. Positive selection was identified for fibrinogen (FG), FIII, FVIII, FIX, and FX in the mammalian Primates and Laurasiatheria and the Sauropsida (reptiles and birds). This showed that the coagulation system in vertebrates was under strong selective pressures, perhaps to adapt against blood-invading pathogens. The comparison of these results with disease-causing mutations reported in FVIII, FIX, and FXI showed that the number of disease-causing mutations, and the probability of positive selection were inversely related to each other. It was concluded that when a site was under positive selection, it was less likely to be associated with disease-causing mutations. In contrast, sites under negative selection were more likely to be associated with disease-causing mutations and be destabilizing. A residue-by-residue comparison of the FVIII, FIX, and FXI sequence alignments confirmed this. This improved understanding of evolutionary changes in FVIII, FIX, and FXI provided greater insight into disease-causing mutations, and better assessments of the codon sites that may be mutated in applications of gene therapy. [ABSTRACT FROM PUBLISHER]

aHUS (atypical haemolytic uraemic syndrome), AMD (age-related macular degeneration) and other diseases are associated with defective AP (alternative pathway) regulation. CFH (complement factor H), CFI (complement factor I), MCP (membrane cofactor protein) and C3 exhibited the most disease-associated genetic alterations in the AP. Our interactive structural database for these was updated with a total of 324 genetic alterations. A consensus structure for the SCR (short complement regulator) domain showed that the majority (37%) of SCR mutations occurred at its hypervariable loop and its four conserved Cys residues. Mapping 113 missense mutations onto the CFH structure showed that over half occurred in the C-terminal domains SCR-15 to -20. In particular, SCR-20 with the highest total of affected residues is associated with binding to C3d and heparin-like oligosaccharides. No clustering of 49 missense mutations in CFI was seen. In MCP, SCR-3 was the most affected by 23 missense mutations. In C3, the neighbouring thioester and MG (macroglobulin) domains exhibited most of 47 missense mutations. The mutations in the regulators CFH, CFI and MCP involve loss-of-function, whereas those for C3 involve gain-of-function. This combined update emphasizes the importance of the complement AP in inflammatory disease, clarifies the functionally important regions in these proteins, and will facilitate diagnosis and therapy. [ABSTRACT FROM AUTHOR]

Complement factor H (CFH) is the major regulator of the central complement protein C3b in the alternative pathway of complement activation. A molecular view of the CFH interaction with native heparan sulfate (HS) is central for understanding the mechanism of how surface-bound CFH interacts with C3b bound to host cell surfaces. HS is composed of sulfated heparin-like S-regions that alternate with desulfated NA-regions. Solution structural studies of heparin (equivalent to the S-regions) and desulfated HS (the NA-regions) by scattering and ultracentrifugation showed that each structure was mostly extended and partially bent, but with greater bending and flexibility in the NA-regions compared to the S-regions. Their solution structures have been deposited in the Protein Data Bank. The largest HS oligosaccharides showed more bent and flexible structures than those for heparin. A folded-back domain structure for the solution structure of the 20 domains in CFH was determined likewise. CFH binds to the S-regions but less so to the NA-regions of HS. The bivalent interaction of CFH-heparin was observed by ultracentrifugation, and binding studies of CFH fragments with heparin-coated sensor chips. In common with other CFH interactions with its physiological and pathophysiological ligands, the CFH-heparin and CFH-C3b interactions have moderate micromolar dissociation constants KD, meaning that these complexes do not fully form in vivo. The combination of the solution structures and binding studies indicated a two-site interaction model of CFH with heparin at cell surfaces. By this, the bivalent binding of CFH to a cell surface is co-operative. Defective interactions at either of the two independent CFH-heparin sites reduce the CFH interaction with surface-bound C3b and lead to immune disorders. [ABSTRACT FROM AUTHOR]

This paper uses longitudinal case studies of HR reform within privatised Jordanian undertakings, with French parent companies, to analyse HRM knowledge transfer across geographical and ‘psychic’ boundaries, following business acquisitions in an emerging Middle Eastern economy. It does this by paying attention to organisational information and control mechanisms utilised by multinational companies (MNCs). The findings indicate that, when working across transcultural settings, MNC managers who pay attention to the intermediating influences of how the parties build common understanding and learn to work together affect the success of inter-unit knowledge transfer. [ABSTRACT FROM PUBLISHER]

FH (Factor H) with 20 SCR (short complement regulator) domains is a major serum regulator of complement, and genetic defects in this are associated with inflammatory diseases. Heparan sulfate is a cell-surface glycosaminoglycan composed of sulfated S-domains and unsulfated NA-domains. To elucidate the molecular mechanism of binding of FH to glycosaminoglycans, we performed ultracentrifugation, X-ray scattering and surface plasmon resonance with FH and glycosaminoglycan fragments. Ultracentrifugation showed that FH formed up to 63% of welldefined oligomers with purified heparin fragments (equivalent to S-domains), and indicated a dissociation constantKd of approximately 0.5 µM. Unchanged FH structures that are bivalently crosslinked at SCR-7 and SCR-20 with heparin explained the sedimentation coefficients of the FH-heparin oligomers. The X-ray radius of gyration, RG, of FH in the presence of heparin fragments 18-36 monosaccharide units long increased significantly from 10.4 to 11.7 nm, and the maximum lengths of FH increased from 35 to 40 nm, confirming that large compact oligomers had formed. Surface plasmon resonance of immobilized heparin with fulllength FH gave Kd values of 1-3 µM, and similar but weaker Kd values of 4-20 µM for the SCR-6/8 and SCR-16/20 fragments, confirming co-operativity between the two binding sites. The use of minimally-sulfated heparan sulfate fragments that correspond largely to NA-domains showed much weaker binding, proving the importance of S-domains for this interaction. This bivalent and co-operative model of FH binding to heparan sulfate provides novel insights on the immune function of FH at host cell surfaces. [ABSTRACT FROM AUTHOR]

The study of the relationship between the complex structures and numerous physiological functions of the glycosaminoglycans (GAGs) heparin and heparan sulfate (HS) has continued to thrive in the past decade. Though it is clear that the monosaccharide sequences of these polysaccharides must determine their ability to modulate the action of growth factors, morphogens, chemokines, cytokines, and many other extracellular proteins, the exact details of this dependence still prove elusive. Sequence determines the 3D structure of GAGs at more than one level; detailed sequences of highly sulfated regions may influence affinity for specific proteins in some cases, but in addition attention has been called to the importance of the length and spacing of these highly sulfated sequences, which are separated by unsulfated domains. Within the sulfated "S-domains", the internal dynamics of the conformationally flexible iduronate pyranose ring have continued to interest NMR spectroscopists and molecular modelers. New studies of the relative degrees of flexibility of sulfated and unsulfated domains lead to an overall model of heparin/HS in which protein-binding, highly sulfated S-domains with well-defined conformations are separated by more flexible NA-domains. [ABSTRACT FROM AUTHOR]

Themes emerging at conference events held at the London School of Economics on 20 March 2009 and 26 March 2010 [ABSTRACT FROM AUTHOR]

The emerging character of the UK government's public sector pay reforms during the second and third (New) Labour terms of office is reviewed and contextualised. Three settings are examined where pay reform has been actively employed – with the accent on harmonisation, simplification and devolution of practice, with the express intention of restoring public service workforce morale, while improving services to clients – namely, local government, the National Health Service and the Higher Education sector. The evidence is interpreted as illustrating undoubted change, but also significant areas where progress has been less than intended, measured against the government's original programme goals. Equal pay considerations appear to have dominated all three projects reviewed: the failure to date of public sector managements to capitalise on opportunities the new pay architecture affords them to change local working practices may be attributed to a combination of factors discussed in the article. These have given rise to tensions as efforts have been pursued to transplant private sector pay techniques, somewhat hastily in some cases, without due consideration of the institutional context within which public services and proximal institutions function. [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented in which the editor discusses an article on unique managerial practice in operating organizations in Western Europe in 1989 by Thurley and Wirdenius, human resource management (HRM) theorizing in 2003 by Gooderham and Brewster, and the HRM total rewards model in 2007 by Davis.

The histone-like nucleoid-structuring protein (H-NS) plays an important role in both DNA packaging and global gene regulation in enterobacteria. Self-association of the N-terminal domain results in polydisperse oligomers that are critical to the function of the protein. This heterogeneity in oligomer size has so far prevented structure determination of the complete oligomerization domain by NMR or X-ray crystallography. In the absence of inorganic salt, the H-NS oligomerization domain is predominantly restricted to an equilibrium between a homodimer and homotetramer, allowing a protein solution to be prepared that is sufficiently homogeneous for successful crystallization. Crystallization was achieved by tailoring the conditions screened to those identified as minimizing the potential disruption of protein-solution homogeneity. This finding provides a significant step towards resolving the structure of this important prokaryotic protein. [ABSTRACT FROM AUTHOR]

The nucleoid-associated protein H-NS and its paralogue StpA are global regulators of gene expression and form an integral part of the protein scaffold responsible for DNA condensation in Escherichia coli and Salmonella typhimurium. Although protein oligomerization is a requirement for this function, it is not entirely understood how this is accomplished. We address this by reporting on the self-association of H-NS and its hetero-association with StpA. We identify residues 1–77 of H-NS as being necessary and sufficient for high-order association. A multi-technique-based approach was used to measure the effects of salt concentration on the size distribution of H-NS and the thermal stability of H-NS and StpA dimers. The thermal stability of the StpA homodimer is significantly greater than that of H-NS1−74. Investigation of the hetero-association of H-NS and StpA proteins suggested that the association of H-NS with StpA is more stable than the self-association of either H-NS or StpA with themselves. This provides a clear understanding of the method of oligomerization of these important proteins in effecting DNA condensation and reveals that the different associative properties of H-NS and StpA allow them to perform distinct, yet complementary roles in the bacterial nucleoid. [ABSTRACT FROM AUTHOR]

The article discusses two conferences that were held in London, England, in March 2007 and March 2008. Topics that were discussed at the conferences included Information and Consultation of Employees (ICE) Regulations and changes that have occurred in regards to the impact that employees have in the way in which companies are managed.

Central repositories of mutations that combine structural, sequence, and phenotypic information in related proteins will facilitate the diagnosis and molecular understanding of diseases associated with them. Coagulation involves the sequential activation of serine proteases and regulators in order to yield stable blood clots while maintaining hemostasis. Five coagulation serine proteases-factor VII ( F7), factor IX ( F9), factor X ( F10), protein C ( PROC), and thrombin ( F2)-exhibit high sequence similarities and all require vitamin K. All five of these were incorporated into an interactive database of mutations named CoagMDB (; last accessed: 9 August 2007). The large number of mutations involved (especially for factor IX) and the increasing problem of out-of-date databases required the development of new database management tools. A text mining tool automatically scans full-length references to identify and extract mutations. High recall rates between 96 and 99% and precision rates of 87 to 93% were achieved. Text mining significantly reduces the time and expertise required to maintain the databases and offers a solution to the problem of locus-specific database management and upkeep. A total of 875 mutations were extracted from 1,279 literature sources. Of these, 116 correspond to Gla domains, 86 to the N-terminal EGF domain, 73 to the C-terminal EGF domain, and 477 to the serine protease domain. The combination of text mining and consensus domain structures enables mutations to be correlated with experimentally-measurable phenotypes based on either low protein levels (Type I) or reduced functional activities (Type II), respectively. A tendency for the conservation of phenotype with structural location was identified. Hum Mutat 29(3), 333-344, 2008. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Purpose - The purpose of this article is to enhance understanding of influences on interaction between corporate personnel and development specialists and line functions associated with expatriating managers. Line managers are expected to accept greater responsibility for people management and development. But line managers' strategies for managing risks inherent in supervising expatriate managers may cause to surface incompatibilities with specialists' corporate "policy conscience" role. A pluralistically inclined perspective on "managerial interest streams" offers insights into inter-group perceptions and behaviour. Design/methodology/approach - Focusing on organisational actors' interpretations, a non-standardised survey by e-mail, covering a small sample of expatriate managers (n = 20) employed in various countries by a large UK-headquartered healthcare retail group, was complemented by semi-structured interviews with personnel and development specialists in a further seven large multinational companies. Findings - Potential tensions around the application of corporate expatriation policy may be attributed to factors "educating" line and specialist orientations to expatriate managers. Originality/value - The value of the paper is in the development of an original model sketching pluralistically located interaction around expatriation management. While limited to an exploratory empirical investigation, the practical implications derive from specification of opportunities and threats to partnership building between those involved in expatriating managers. [ABSTRACT FROM AUTHOR]

Atypical hemolytic uremic syndrome (aHUS) is a disease of hemolytic anemia, thrombocytopenia, and renal failure associated with defective alternative pathway (AP) complement control. Previously, we presented a database () focusing on aHUS mutations in the Factor H gene ( CFH). Here, new aHUS mutations are reported for the complement regulatory proteins Factor H (FH), Factor I (FI), and membrane cofactor protein (MCP). Additional mutations or polymorphisms within CFH have been associated with membranoproliferative glomerulonephritis (MPGN) and age-related macular degeneration (AMD). Accordingly, the database now includes substitutions that predispose to aHUS, MPGN, and AMD. For this, structural models for the domains in MCP and FI were developed using homology modeling. With this new database, patients with mutations in more than one gene can be displayed and interpreted in a coherent manner. The database also includes SNP polymorphisms in CFH, MCP, and IF. There are now a total of 167 genetic alterations, including 100 in CFH, 43 in MCP, and 24 in IF. The mutations characterize clinical outcomes that vary from several AMD-associated polymorphisms to those associated with aHUS, MPGN, or FI deficiency. A consensus short complement regulator (SCR) domain structure facilitated the interpretations of aHUS mutations. Specific locations within this consensus domain often correlate with the occurrence of clinical phenotypes. The AMD Tyr402His polymorphism is structurally located at a hotspot for several aHUS mutations. The database emphasizes the causative role of the alternative pathway of complement in disease and provides a repository of knowledge to assist future diagnosis and novel therapeutic approaches. Hum Mutat 28(3), 222-234, 2007. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Doublecortin is a neuronal microtubule-stabilising protein, mutations of which cause mental retardation and epilepsy in humans. How doublecortin influences microtubule dynamics, and thereby brain development, is unclear. We show here by video microscopy that purified doublecortin has no effect on the growth rate of microtubules. However, it is a potent anti-catastrophe factor that stabilises microtubules by linking adjacent protofilaments and counteracting their outward bending in depolymerising microtubules. We show that doublecortin-stabilised microtubules are substrates for kinesin translocase motors and for depolymerase kinesins. In addition, doublecortin does not itself oligomerise and does not bind to tubulin heterodimers but does nucleate microtubules. In cells, doublecortin is enriched at the distal ends of neuronal processes and our data raise the possibility that the function of doublecortin in neurons is to drive assembly and stabilisation of non-centrosomal microtubules in these doublecortin-enriched distal zones. These distinct properties combine to give doublecortin a unique function in microtubule regulation, a role that cannot be compensated for by other microtubule-stabilising proteins and nucleating factors. [ABSTRACT FROM AUTHOR]

Factor H (FH) is a central complement regulator comprised of 20 short complement repeat (SCR) domains. Nucleotide changes within this gene ( CFH) have been observed in patients with hemolytic uremic syndrome (HUS), and also membranoproliferative glomerulonephritis and age-related macular degeneration. All parts of FH are affected, but many mutations are clustered in the C-terminal part of FH. Up to now, structural analyses of HUS have been based on SCR-20, a domain that is involved in FH interactions with C3b, heparin, and endothelial cells. In order to identify the structural and functional consequence of HUS mutations, further disease-associated mutations were analyzed in terms of homology and nuclear magnetic resonance (NMR) models for factor H SCR domains. An interactive web database of 54 human HUS-associated mutations and others was created from the literature (www.FH-HUS.org). This has comprehensive search and analysis tools, integrating phenotypic and genetic data with structural analysis. Each mutation can be highlighted on the SCR structure together with the patient FH and C3 levels where available. Two new insights were obtained from our collection of data. First, phenotypic data on FH clarify our previously-proposed classification of Type I and Type II disorders that both lead to HUS, where Type I affects FH secretion and folding, and Type II leads to expressed protein in plasma that is functionally defective. Second, the new mutations show more clearly that SCR domains from SCR-16 to SCR-19 are important for the ligand binding activities of FH as well as SCR-20. This FH web database will facilitate the interpretation of new mutations and polymorphisms when these are identified in patients, and it will clarify the functional role of FH. Hum Mutat 27(1), 21-30, 2006. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Boardroom reward continues to attract controversy, despite the structural changes in corporate governance arrangements over the past decade. This study responds to Pettigrew's (1992 ) call to eschew over-ambitious attempts to demonstrate causality in the area of executive management and firm performance, in favour of redressing the overwhelmingly prescriptive bias in the literature. A simple but important task is to 'begin to provide some basic descriptive findings about boards and their directors,' and open up 'the black box of board behaviour'--in this case, that of board remuneration committees. Interpretations of comparative market signals play a part in deliberations between the leading actors responsible for determining executive directors' salary, bonuses and other emoluments. But the position is more deeply textured than the reified influence of (global) market forces sometimes implied in the normative literature. The study reported, based on qualitative interviews, taps in to the nuances of decision taking in respect of boardroom reward management, including remuneration committee members' reactions to corporate governance reforms. Such initiatives locate non-executive directors in the role of intermediaries in the principal-agent relationship, explicitly assigned to resolve the conflict of interest inherent in boardroom remuneration systems, while simultaneously they are expected to play a team role as board members responsible for the overall strategy and operation of the company. The study is indicative: an attempt to open up research questions around the context and process of boardroom reward management that earlier analyses may have ignored or overlooked. [ABSTRACT FROM AUTHOR]

Factor XI (FXI) is the zymogen of a serine protease enzyme in the intrinsic pathway of blood coagulation and is an important factor in the creation of a stable fibrin clot. Deficiency of FXI leads to an injury-related bleeding disorder and is remarkable for the lack of correlation between bleeding symptoms and FXI coagulant activity (FXI:C). The FXI protein is composed of five domains: four tandem repeat domains of ∼80 residues known as Apple (Ap) domains, and the catalytic serine protease (Sp) domain. A total of 65 mutations throughout the FXI gene ( F11) have been reported in FXI deficient patients. An interactive web database of these mutations has been created () that integrates the phenotypic data with genetic data and structural homology models for the five FXI domains. The database provides a central repository for all reported genetic alterations within F11. With the use of recently developed visualization tools, each mutation can be highlighted on the structural models of the FXI domains together with an appropriate survey of patient data, such as FXI:C levels and FXI antigen levels. The database also enables new F11 mutations to be interpreted. The interactive design of this database will lead to a more comprehensive comparative understanding of the genetic factors that influence bleeding risk. Hum Mutat 26(3), 192-198, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Globalization may be interrogated from several angles: its implicit grounding in unitarist and neoliberal ideology; its status in relation to socially embedded institutions and its assumed universalism and run away power. Human resource management as an international discipline is an emerging area of academic study. Comparative analysis facilitates attempts to distinguish the essential from the accidental, the simple from the complex, the primary from the derived. Comparative variation in the ways academic commentators approach the concept of globalization and the consequences for people management and development, may profitably be evaluated heuristically. Alternative perspectives are presented to compare and contrast the ways in which scholars are interpreting globalization and its consequences for investment in human capital, theoretically and in practice. The article contributes to scoping the empirical research agenda emerging from such considerations, giving rise to implications for those involved in trans-national training and development.

Summary. Factor X (FX) deficiency is a rare autosomal recessive disorder. The phenotype and genotype of 15 Iranian patients with FX deficiency from 13 unrelated families with a high frequency of consanguinity were analysed. Five different assays identified four patients from three families with a discrepancy between low-FX coagulant activity (FX:C) and higher-FX antigen (FX:Ag) (a type II deficiency). The remaining 11 patients had parallel reductions of FX:C and FX:Ag (a type I deficiency). Nine different homozygous candidate mutations were identified, of which eight were novel. The four type II cases were associated with an Arg(-1)Thr missense mutation in the prepropeptide: Arg(-1) is highly conserved in all vitamin K-dependent proteins. Four type I mutations (Gly78Asp, Cys81Tyr, Gly94Arg and Asp95Glu) were localized to the EGF-1 and EGF-2 domains, for which molecular views showed that the protein folding would be disrupted. The type I mutation Gly222Asp was localized in the catalytic domain of FX, and is sufficiently close to the Asp-His-Ser catalytic triad to disrupt its correct protein folding. The two type I splice site mutations were IVS1+3, A→T and IVS2–3, T→G. These novel homozygous FX mutations were consistent with their phenotypes and agree with experimental data from knockout mice, indicating that FX is an essential protein for survival. [ABSTRACT FROM AUTHOR]

Multinational corporations are increasingly reliant on a cadre of key individuals for organizational cohesion and to implement globalization strategies. Survey evidence, however, suggests that many firms are mismanaging the performance, reward and recognition of these "global champions." Governance of corporations listed on the world's stock exchanges is a topic of controversy commentators, investors and the wider public. Firms of all complexions, but especially large Multi national enterprises, are moving on from the organizational forms that characterized traditional management control structures accompanying foreign direct investment. Corporate governance that seeks to align employee and shareholder fortunes suggests that performance is the basis for differentiating rewards among employees, irrespective of activity or location. However, performance management and incentive pay systems are complicated for companies whose reward policy requires expatriate balance sheet calculations.

Many immunologically relevant proteins possess multidomain structures. Molecular structures both at the level of the individual domain and that of the intact protein are required for a full appreciation of function and control. Two recently develop structural approaches are reviewed here. Analogy modelling methods are based on the current understanding of many protein structures, and make possible the identification of folds for superfamilies of unknown structures. An integrated multidisciplinary predictive approach has been successfully applied to the von Willebrand factor type A, proteoglycan tandem repeat and factor I/membrane attack complex domains. The available experimental and predictive evidence is assembled in order to identify a known three-dimensional structure related to the unknown one of interest. Neutron and X-ray scattering curve modelling provides information on the full multidomain structure in solution. As scattering curves can be calculated from known atomic structures, the present availability of structures for many domains in conjunction with tight constraints based on these structures and the covalent connections between them results in a small family of allowed best-fit structures for a given scattering curve. The curve-fit procedure can be automated, and whole multidomain structures can be determined to a positional precision of the order of 0.2-1 nm. Such models are informative on the steric accessibility of each domain and their functional activity, and this is illustrated for antibody, cell-surface and complement proteins. [ABSTRACT FROM AUTHOR]

Amino acid sequences, carbohydrate compositions and residue volumes are used to compare critically calculations of partial specific volumes v, neutron scattering matchpoints and 280-nm absorption coefficients with experimental v values for proteins and glycoproteins. The v values that are obtained from amino acid densitometry underestimate experimental 3 values by 0.01-0.02 ml/g while the v values from crystallographic volumes overestimate the experimental v values by 0.04-0.05 ml/g. An intermediate consensus volume set of amino-acid residue volumes is proposed in order to predict experimental v values using sequence information. The method is extended to carbohydrates and glycoproteins. Neutron scattering matchpoints can be calculated from crystallographic residue volumes on the basis of the non-exchange of 10% of the main-chain NH protons. Crystallographic results on protein-bound water are used to account for the experimental values of v and matchpoints. Finally, 280-nm absorption coefficients, A1%, 1 cm280, of 5-27 are found to be well predicted by the Wetlaufer procedure based on the totals of Trp, Tyr and Cys residues. Average errors are ± 0.7, and the 10 experimental A1%, 1 cm280, values can be larger than the predicted values by 3%. [ABSTRACT FROM AUTHOR]

Solution scattering experiments using both X-rays and neutrons are reported for human complement component C3 and up to six other glycoprotein fragments that are derived from C3. The X-ray and neutron molecular masses and neutron matchpoints are in agreement with the known primary sequence of C3. The X-ray radius of gyration RG of C3 is 5.2 nm and is similar for the related forms C3u, C3(a + b) and C3 b. The X-ray cross-sectional radius of gyration Rxs of C3 b is however less than that of C3, C3u and C3(a + b). The major fragments of C3b, namely C3c and C3dg, were studied. The RG of C3c is 4.7 nm and for C3dg is 2.9 nm. C3c and C3dg do not interact when they coexist in solution in equimolar amounts. When C3u is cleaved into iC3u, the RG of iC3u increases to 5.9 nm and its Rxs decreases, showing that C3c and C3dg behave as independent entities within the parent glycoprotein. Analyses of the neutron RG and Rxs values by contrast variation techniques confirm the X-ray analyses, and show no evidence for significant hydrophobic or hydrophilic domains within C3 or any of its fragments. Shape analyses show that C3, C3c and C3dg are elongated panicles. Debye models were developed using the scattering curve out to Q = 1.6 nm-1. These show that C3 and C3c resemble oblate ellipsoids while C3dg resembles a prolate ellipsoid. C3dg lies on the long edge of C3c within C3. The dimensions of the models are 18 nm x 2 nm x 10 nm for C3, 18 nm x 2 nm x 7 nm for C3c and 10 nm x 2 nm x 3 nm for C3dg. These models are compatible with analyses of the scattering curve RG and Rxs values, data from sedimentation coefficients, and images of C3 and C3c seen by electron microscopy. [ABSTRACT FROM AUTHOR]

Two forms of α1 acid glycoprotein (orosomucoid) have been studied using small-angle neutron and X-ray scattering techniques; in one form all the five glycan chains were biantennary, while in the other they were either triantennary or tetraantennary. The radius of gyration RG was found to be sensitive to salt for the biantennary form, but to be unchanged up to an ionic strength of 3 M for the triantennary and tetraantennary forms. Conformational heterogeneity is thus associated with carbohydrate heterogeneity. Hydrodynamic frictional coefficients (f) confirm these findings. Simple models of α1 acid glycoprotein were developed to account for the RG and (f) values. These show that the compact conformation is slightly more elongated than a globular protein and that the expanded biantennary conformation has a most extended carbohydrate structure. Up to half of the surface of the compact shape can be covered by carbohydrate residues. [ABSTRACT FROM AUTHOR]

Small-angle neutron scattering experiments on α1 acid glycoprotein showed that it has a molecular weight of 37000 and a matchpoint of 44.7% ²H2O The molecular weight, the matchpoint and a &vmacr; of 0.704 ml/g are in agreement with the primary sequence and standard residue volumes for amino acids and carbohydrates. The radius of gyration RG of α1 acid glycoprotein was found to be independent of concentration in the range 2- 11 mg/ml, but increases on going from a buffer containing 0.2 MnaCl to one containing 1 M NaCl. A contrast variation study showed that the RG at infinite contrast is 2.47 nm fir the expanded form and 2.19 nm for the contracted form, and that the two Stuhrmann α values are similar at 27 x 10-5. The latter is greater than the expected for globular proteins and are explained by the surface disposition of the five glycan chains on a core of protein in α1 acid glycoprotein. Modeling calculations account for the two RG values in which for the expanded form the glycan chains extend out into the solvent and for the contracted form they either fold back or are splayed our such that they are able to interact with surface of the protein core. [ABSTRACT FROM AUTHOR]

1. Proton magnetic resonance spectra at 270 MHz of polymyxin B, a cationic oligopeptide antibiotic, show the influence of the inorganic counteranion present in solution. 2. Hydrogen-deuterium exchange rates for the amide protons are of two types, depending on whether the anion is monovalent or polyvalent. Polyvalent anions catalyse the acid-catalysed reaction more than the monovalent anions. 3. The structure in solution was monitored using the proton signals of the amides, the phenylalanine aromatic protons, and the ieucine methyl and γ-CH protons in several polymyxin salts. The temperature coefficients of the chemical shifts of the N-H protons are used to identify two β turns in the cyclic ring of polymyxin B. The variation in chemical shift of the N-H protons, the aromatic protons and the leucine protons are correlated with anionic size and electronegativity. [ABSTRACT FROM AUTHOR]