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The polysialic acid (polySia) is a unique carbohydrate polymer produced on the surface of Neuronal Cell Adhesion Molecule (NCAM) in a number of cancer cells, and strongly correlates with the migration and invasion of tumor cells and with aggressive, metastatic disease and poor clinical prognosis in the clinic. Its synthesis is catalyzed by two polysialyltransferases (polySTs), ST8SiaIV (PST) and ST8SiaII (STX). Selective inhibition of polySTs, therefore, presents a therapeutic opportunity to inhibit tumor invasion and metastasis due to NCAM polysialylation. It has been proposed that NCAM polysialylation could be inhibited by two types of heparin inhibitors, low molecular heparin (LMWH) and heparin tetrasaccharide (DP4). This review summarizes how the interactions between Polysialyltransferase Domain (PSTD) in ST8SiaIV and CMP-Sia, and between the PSTD and polySia take place, and how these interactions are inhibited by LMWH and DP4. Our NMR studies indicate that LMWH is a more effective inhibitor than DP4 for inhibition of NCAM polysialylation. The NMR identification of heparin-binding sites in the PSTD may provide insight into the design of specific inhibitors of polysialylation.

AarF domain containing kinase 4 (ADCK4) is identified as a candidate gene associated with hereditary nephrotic syndrome (NS). Kruppel-like factor 5 (KLF5) is reported to promote podocyte survival by blocking the ERK/p38 MAPK pathways. Both ADCK4 and KLF5 are involved in the occurrence and development of podocyte disease, but their interaction remains unclear. Firstly, we found that the mRNA levels of ADCK4 and KLF5 decreased in NS patients, and both levels showed an obvious linear relationship. Secondly, we cloned the ADCK4 promoter region and examined its promoter activity in Hela, A549, and HEK 293 cell lines. Deletion analysis showed that the region - 116/- 4 relative to the transcriptional start site (TSS) was the core region of ADCK4 promoter. Thirdly, mutation analysis showed that putative binding sites for KLF5 contributed to the ADCK4 promoter activity. In HEK293 cells, we found that KLF5 upregulated the mRNA and protein levels of ADCK4. Finally, our chromatin immunoprecipitation assay found that KLF5 could bind to the specific region of ADCK4 promoter. These results showed that KLF5 can positively regulate the transcriptional activity of ADCK4.

Background:Inhibition of α-amylase activity is an important strategy in the treatment of diabetes mellitus. An important treatment for diabetes mellitus is to reduce the digestion of carbohydrates and blood glucose concentrations. Inhibiting the activity of carbohydrate-degrading enzymes such as α-amylase and glucosidase significantly decreases the blood glucose level. Most inhibitors of α-amylase have serious adverse effects, and the α-amylase inactivation mechanisms for the design of safer inhibitors are yet to be revealed.Objective:In this study, we focused on the inhibitory effect of Zn2+ on the structure and dynamic characteristics of α-amylase from Anoxybacillus sp. GXS-BL (AGXA), which shares the same catalytic residues and similar structures as human pancreatic and salivary α-amylase (HPA and HSA, respectively).Methods:Circular dichroism (CD) spectra of the protein (AGXA) in the absence and presence of Zn2+ were recorded on a Chirascan instrument. The content of different secondary structures of AGXA in the absence and presence of Zn2+ was analyzed using the online SELCON3 program. An AGXA amino acid sequence similarity search was performed on the BLAST online server to find the most similar protein sequence to use as a template for homology modeling. The pocket volume measurer (POVME) program 3.0 was applied to calculate the active site pocket shape and volume, and molecular dynamics simulations were performed with the Amber14 software package.Results:According to circular dichroism experiments, upon Zn2+ binding, the protein secondary structure changed obviously, with the α-helix content decreasing and β-sheet, β-turn and randomcoil content increasing. The structural model of AGXA showed that His217 was near the active site pocket and that Phe178 was at the outer rim of the pocket. Based on the molecular dynamics trajectories, in the free AGXA model, the dihedral angle of C-CA-CB-CG displayed both acute and planar orientations, which corresponded to the open and closed states of the active site pocket, respectively. In the AGXA-Zn model, the dihedral angle of C-CA-CB-CG only showed the planar orientation. As Zn2+ was introduced, the metal center formed a coordination interaction with H217, a cation-π interaction with W244, a coordination interaction with E242 and a cation-π interaction with F178, which prevented F178 from easily rotating to the open state and inhibited the activity of the enzyme.Conclusion:This research may have uncovered a subtle mechanism for inhibiting the activity of α-amylase with transition metal ions, and this finding will help to design more potent and specific inhibitors of α-amylases.

Background:The polysialic acid (polySia) is a unique carbohydrate polymer produced on the surface Of Neuronal Cell Adhesion Molecule (NCAM) in a number of cancer cells, and strongly correlates with the migration and invasion of tumor cells and with aggressive, metastatic disease and poor clinical prognosis in the clinic. Its synthesis is catalyzed by two polysialyltransferases (polySTs), ST8SiaIV (PST) and ST8SiaII (STX). Selective inhibition of polySTs, therefore, presents a therapeutic opportunity to inhibit tumor invasion and metastasis due to NCAM polysialylation. Heparin has been found to be effective in inhibiting the ST8Sia IV activity, but no clear molecular rationale. It has been found that polysialyltransferase domain (PSTD) in polyST plays a significant role in influencing polyST activity, and thus it is critical for NCAM polysialylation based on the previous studies.Objective:To determine whether the three different types of heparin (unfractionated hepain (UFH), low molecular heparin (LMWH) and heparin tetrasaccharide (DP4)) is bound to the PSTD; and if so, what are the critical residues of the PSTD for these binding complexes?Methods:Fluorescence quenching analysis, the Circular Dichroism (CD) spectroscopy, and NMR spectroscopy were used to determine and analyze interactions of PSTD-UFH, PSTD-LMWH, and PSTD-DP4.Results:The fluorescence quenching analysis indicates that the PSTD-UFH binding is the strongest and the PSTD-DP4 binding is the weakest among these three types of the binding; the CD spectra showed that mainly the PSTD-heparin interactions caused a reduction in signal intensity but not marked decrease in α-helix content; the NMR data of the PSTD-DP4 and the PSTDLMWH interactions showed that the different types of heparin shared 12 common binding sites at N247, V251, R252, T253, S257, R265, Y267, W268, L269, V273, I275, and K276, which were mainly distributed in the long α-helix of the PSTD and the short 3-residue loop of the C-terminal PSTD. In addition, three residues K246, K250 and A254 were bound to the LMWH, but not to DP4. This suggests that the PSTD-LMWH binding is stronger than the PSTD-DP4 binding, and the LMWH is a more effective inhibitor than DP4.Conclusion:The findings in the present study demonstrate that PSTD domain is a potential target of heparin and may provide new insights into the molecular rationale of heparin-inhibiting NCAM polysialylation.

Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in childhood driven by aberrant pathways of T-cell activation. T helper 17 (Th17)/regulatory T cell (Treg) imbalance plays critical roles in the pathogenesis of arthritis. MicroRNA-125b (miR-125b) was upregulated after the activation of the initial CD4+ T cells, and could regulate the differentiation of CD4+ T cells. However, the effects of miR-125b on Th17/Treg imbalance and differentiation of Th17/Treg cells remain unknown. In this study, we evaluated the expression of miR-125b in the peripheral blood mononuclear cells (PBMCs) of children with JIA, and the relationship of miR-125b with Th17/Treg imbalance. Then, we used lentivirus vector-mediated overexpression technology to investigate the regulatory function of miR-125b in CD4+ T cells or dendritic cell/CD4+ T co-culture system. Decreased miR-125b expression in PBMCs and CD4+ T cells of JIA patients was negatively correlated with the ratio of Th17/Treg cells. It also correlated negatively with retinoic acid receptor-related orphan receptor γt but positively with Forkhead box protein 3 at transcriptional levels. Furthermore, we found that miR-125b overexpression inhibited Th17 cell differentiation, whereas facilitated the differentiation of Treg cells. MiR-125b upregulation led to the decrease of Th17-secreting cytokines but the increase of the Treg-secreting cytokines. Our results demonstrate that miR-125b participated in regulating Th17/Treg cell differentiation and imbalance in JIA patients. These findings provide novel insight into the critical role of miR-125b in the Th17/Treg imbalance of JIA, and raise the distinct possibility that miR-125b may prove to be a potential therapeutic target for JIA.

Di-n-butyl phthalate (DBP) is a kind of ubiquitous chemical linked to hormonal disruptions that affects male reproductive system. However, the mechanism of DBP-induced germ cells toxicity remains unclear. Here, we demonstrate that DBP induces reduction of proliferation, increase of apoptosis and DNA damage dependent on the PTEN/AKT pathway. Mechanistically, DBP decreases PTEN promoter methylation and increases its transcriptional activity, leading to increased PTEN expression. Notably, DNMT3b is confirmed as a target of miR-29b and miR-29b-mediated status of PTEN methylation is involved in the effects of DBP treatment. Meanwhile, DBP decreases AKT pathway expression via increasing PTEN expression. In addition, the fact that DBP decreases the sperm number and the percentage of motile and progressive sperm is associated with downregulated AKT pathway and sperm flagellum-related genes. Collectively, these findings indicate that DBP induces aberrant PTEN demethylation, leading to inhibition of the AKT pathway, which contributes to the reproductive toxicity.

The expression changes of CD2-associated protein (CD2AP) can lead to kidney diseases with proteinuria, including nephrotic syndrome (NS). A recent study reported that miRNAs may be important transcriptional regulators. In this study, we found increased expression of miR-939-5p and decreased expression of CD2AP in the peripheral blood of patients with NS. However, miR-939-5p did not show a regulatory effect on the 3'-untranslated region of CD2AP. The expression levels of specific protein 1 and adenovirus E2 promoter-binding factor 1, important transcription regulators in the promoter region of CD2AP, were also not affected by microRNA (miR)-939-5p. We confirmed that miR-939-5p is in the nucleus by fluorescent in situ hybridization and cytoplasmic separation polymerase chain reaction. The promoter plasmid and miR-939-5p were cotransfected into HEK-293 cells, and the luciferase reporter gene assay was used to analyze the promoter activity. We found that miR-939-5p binds to a specific sequence in the CD2AP promoter. miR-939-5p was confirmed to reduce the recruitment of RNA polymerase II to the CD2AP promoter region by chromatin immunoprecipitation. These findings improve our understanding of the mechanism of miR-939-5p in NS and provide potential molecular therapeutic targets for NS.

Background: α-Amylases are starch-degrading enzymes and used widely, the study on thermostability of α-amylase is a central requirement for its application in life science and biotechnology. Objective: In this article, our motivation is to study how the effect of Ca2+ ions on the structure and thermal characterization of α-amylase (AGXA) from thermophilic Anoxybacillus sp.GXS-BL. Methods: α-Amylase activity was assayed with soluble starch as the substrate, and the amount of sugar released was determined by DNS method. For AGXA with calcium ions and without calcium ions, optimum temperature (Topt), half-inactivation temperature (T50) and thermal inactivation (halflife, t1/2) was evaluated. The thermal denaturation of the enzymes was determined by DSC and CD methods. 3D structure of AGXA was homology modeled with α-amylase (5A2A) as the template. Results: With calcium ions, the values of Topt, T50, t1/2, Tm and ΔH in AGXA were significantly higher than those of AGXA without calcium ions, showing calcium ions had stabilizing effects on α-amylase structure with the increased temperature. Based on DSC measurements AGXA underwent thermal denaturation by adopting two-state irreversible unfolding processes. Based on the CD spectra, AGXA without calcium ions exhibited two transition states upon unfolding, including α- helical contents increasing, and the transition from α-helices to β-sheet structures, which was obviously different in AGXA with Ca2+ ions, and up to 4 Ca2+ ions were located on the inter-domain or intra-domain regions according to the modeling structure. Conclusion: These results reveal that Ca2+ ions have pronounced influences on the thermostability of AGXA structure.

CD80 has been known to be a co-stimulatory factor expressed in antigen presenting cells (APCs) involved in T-cell activation. It can be expressed in non-bone marrow-derived cells induced by lipopolysaccharide (LPS) or other stimulators, and directly involved in the pathogenesis following T cell activation. However, the intricate transcription mechanisms that underlying the upregulation of CD80 expression levels in LPS-activated non-bone marrow-derived cells is still unknown. LncRNAs are confirmed to be involved in transcriptional regulation by influencing transcription factors. Therefore, we wanted to determine whether the lncRNA MALAT1, which has been found to be related to LPS-induced inflammation, could regulate the transcription of CD80. Our results showed that CD80 was upregulated in low-dose LPS-activated A549 cells in a NF-κB-dependent manner. The lncRNA MALAT1 can interfere with NF-κB activation and disrupt its binding efficiency with the CD80 promoter. Thus, the lncRNA MALAT1 can regulate CD80 transcription via the NF-κB signaling pathway in the LPS-activated A549 cell line.

Polysialic acid (polySia) is an unusual glycan that posttranslational modifies neural cell adhesion molecule (NCAM) proteins in mammalian cells. The up-regulated expression of polySia-NCAM is associated with tumor progression in many metastatic human cancers and in neurocognitive processes. Two members of the ST8Sia family of &alpha, 2,8-polysialyltransferases (polySTs), ST8Sia II (STX) and ST8Sia IV (PST) both catalyze synthesis of polySia when activated cytidine monophosphate(CMP)-Sialic acid (CMP-Sia) is translocate into the lumen of the Golgi apparatus. Two key polybasic domains in the polySTs, the polybasic region (PBR) and the polysialyltransferase domain (PSTD) areessential forpolysialylation of the NCAM proteins. However, the precise molecular details to describe the interactions required for polysialylation remain unknown. In this study, we hypothesize that PSTD interacts with both CMP-Sia and polySia to catalyze polysialylation of the NCAM proteins. To test this hypothesis, we synthesized a 35-amino acid-PSTD peptide derived from the ST8Sia IV gene sequence and used it to study its interaction with CMP-Sia, and polySia. Our results showed for the PSTD-CMP-Sia interaction,the largest chemical-shift perturbations (CSP) were in amino acid residues V251 to A254 in the short H1 helix, located near the N-terminus of PSTD. However, larger CSP values for the PSTD-polySia interaction were observed in amino acid residues R259 to T270 in the long H2 helix. These differences suggest that CMP-Sia preferentially binds to the domain between the short H1 helix and the longer H2 helix. In contrast, polySia was principally bound to the long H2 helix of PSTD. For the PSTD-polySia interaction, a significant decrease in peak intensity was observed in the 20 amino acid residues located between the N-and C-termini of the long H2 helix in PSTD, suggesting a slower motion in these residues when polySia bound to PSTD. Specific features of the interactions between PSTD-CMP-Sia, and PSTD-polySia were further confirmed by comparing their 800 MHz-derived HSQC spectra with that of PSTD-Sia, PSTD-TriSia (DP 3) and PSTD-polySia. Based on the interactions between PSTD-CMP-Sia, PSTD-polySia, PBR-NCAM and PSTD-PBR, these findingsprovide a greater understanding of the molecular mechanisms underlying polySia-NCAM polysialylation, and thus provides a new perspective for translational pharmacological applications and development by targeting the two polysialyltransferases.

ST8Sia II (STX) is a highly homologous mammalian polysialyltransferase (polyST), which is a validated tumor-target in the treatment of cancer metastasis reliant on tumor cell polysialylation. PolyST catalyzes the synthesis of α2,8-polysialic acid (polySia) glycans by carrying out the activated CMP-Neu5Ac (Sia) to N- and O-linked oligosaccharide chains on acceptor glycoproteins. In this review article, we summarized the recent studies about intrinsic correlation of two polybasic domains, Polysialyltransferase domain (PSTD) and Polybasic region (PBR) within ST8Sia II molecule, and suggested that the critical amino acid residues within the PSTD and PBR motifs of ST8Sia II for polysialylation of Neural cell adhesion molecules (NCAM) are related to ST8Sia II activity. In addition, the conformational changes of the PSTD domain due to point mutations in the PBR or PSTD domain verified an intramolecular interaction between the PBR and the PSTD. These findings have been incorporated into Zhou’s NCAM polysialylation/cell migration model, which will provide new perspectives on drug research and development related to the tumor-target ST8Sia II.

Saponin PH, akemisaponins E, saponin PJ1 and scheffoleoside A, the main bioactive triterpene saponins of Chinese traditional medicine Akebia trifoliata, contribute to its diuretic pharmacological activity. Because of interactions of the multiple ingredients in vivo, pharmacokinetic studies of multiple triterpenes after administration of A. trifoliata extract are essential to clarify their pharmacological effects. The purpose of this study was to develop an efficient and sensitive UHPLC-MS/MS method for simultaneous determination of these four triterpene saponins in rat plasma. The biosamples were prepared by liquid-liquid extraction with n-butanol. The chromatographic separation was performed on a Phenomenex Luna® C18 (150 × 2 mm, 3 μm) with a mobile phase consisting of acetonitrile and water at a flow rate of 0.5 mL/min. The MS/MS system was operated in a negative multiple reaction monitoring mode, and the precursor-product ion transitions were optimized as m/z 941.6 → 471.1 for saponin PH, 941.7 → 471.2 for akemisaponins E, 1089.7 → 601.1 for saponin PJ1 , 957.6 → 487.4 for scheffoleoside A and 799.5 → 637.3 for ginsenoside Rg1 (Rg1 , internal standard). Method validation parameters (calibration curve linearity, lower limit of detection, recovery, matrix effect, intra- and inter-day precision) were within the acceptable ranges. This is the first reported on the UHPLC-MS/MS detection of saponin PH, akemisaponins E, saponin PJ1 and scheffoleoside A, and applied to a preclinical pharmacokinetic study after oral administration of A. trifoliata extract in rats. This study provides a basis for clinical application and further development of A. trifoliata extract.

Polysialic acid (polySia) is a novel glycan that posttranslationally modifies neural cell adhesion molecules (NCAMs) in mammalian cells. Up-regulation of polySia-NCAM expression or NCAM polysialylation is associated with tumor cell migration and progression in many metastatic cancers and neurocognition. It has been known that two highly homologous mammalian polysialyltransferases (polySTs), ST8Sia II (STX) and ST8Sia IV (PST), can catalyze polysialylation of NCAM, and two polybasic domains, polybasic region (PBR) and polysialyltransferase domain (PSTD) in polySTs play key roles in affecting polyST activity or NCAM polysialylation. However, the molecular mechanisms of NCAM polysialylation and cell migration are still not entirely clear. In this minireview, the recent research results about the intermolecular interactions between the PBR and NCAM, the PSTD and cytidine monophosphate-sialic acid (CMP-Sia), the PSTD and polySia, and as well as the intramolecular interaction between the PBR and the PSTD within the polyST, are summarized. Based on these cooperative interactions, we have built a novel model of NCAM polysialylation and cell migration mechanisms, which may be helpful to design and develop new polysialyltransferase inhibitors.

Neonatal respiratory distress syndrome (NRDS) is a leading cause of morbidity in premature newborns and is a common reason for admission to the neonatal intensive care unit (NICU). Recent studies found that the pathogenesis of NRDS is not simply lung immaturity. Apoptosis is an essential process for the development and maturation of the lungs. In this study, we report a critical role of lncRNA MALAT1 in regulating CD80 transcription in the NRDS-associated apoptosis via binding with NF-κB. We first showed MALAT1 and CD80 were highly expressed in the peripheral blood mononuclear cells of NRDS with infection exposure. Then we found MALAT1 expressions were significantly increased by the treatment of LPS. We confirmed knockdown of MALAT1 promoted cell viability by CCK-8 assays, cell apoptosis by flow cytometric assays and cytoskeleton destruction by immunocytochemistry. We confirmed CD80 expression level was associated with cell apoptosis by affecting PARP and caspase-3. Then we demonstrated knockdown of MALAT1 promoted CD80 transcription in A549 cells. Furthermore, we confirmed that MALAT1 downregulated transcriptional expression of CD80 by interfering with NF-κB activation and disrupting its binding efficiency with the CD80 promoter in the cell nucleus. In conclusion, we first identified lncRNA MALAT1 as an important prognosis maker for NRDS patients. Most significantly, this study then demonstrated a novel regulatory function of knocked-down MALAT1 on the transcriptional level of CD80 by enhancing the binding of NF-κB to CD80 promoter. Since the interaction between MALAT1 and CD80 plays an essential role in the cell apoptosis of NRDS, our findings demonstrate the possibility of using MALAT1 as therapeutic target for treatment of NRDS, and extend existing knowledge about the molecular mechanism that underlies NRDS pathogensis.

All-trans retinoic acid (ATRA), an active metabolite of vitamin A, plays an important role in regulating cell differentiation, proliferation, and apoptosis. It was reported that ATRA could cause an up-regulation of protein expression of CD2AP in nephrotic animals. However, the mechanism of ATRA-mediated up-regulation is not well understood. In the present study, deletion analysis and luciferase assays demonstrated that ATRA caused a marked increase in the activity of the CD2AP promoter, and the region between nt -599 and -328 from the transcription start site, where there are two clusters of Sp1/3 binding sites, was indispensable for ATRA-mediated up-regulation. Chromatin immunoprecipitation assays revealed that ATRA activated the CD2AP transcription through enhancing the DNA-binding activity of Sp1 and Sp3 with the CD2AP promoter. Taken together, this study provided evidence for the first time showing the stimulating effect of ATRA on CD2AP and new therapeutic strategies for the treatment of nephritic syndrome and other associated diseases of CD2AP deficiency.

(2R,3R)-2,3-Butanediol has many industrial applications, such as it is used as an antifreeze agent and low freezing point fuel. In addition, it is particularly important to provide chiral groups in drugs. In recent years, this valuable bio-based chemical has attracted increasing attention, and significant progress has been made in the development of microbial cell factories for (2R,3R)-2,3-butanediol production. This article reviews recent advances and challenges in microbial routes to (2R,3R)-2,3- butanediol production, and highlights the metabolic engineering and synthetic biological approaches used to improve titers, yields, productivities, and optical purities. Finally, a systematic and integrative strategy for developing high-performance microbial cell factories is proposed.

Cyclic GMP-AMP synthase (cGAS, cGAMP synthase) plays crucial roles in autoimmune disease, anti-tumor response, anti-senescence and anti-inflammatory response. Many studies have focused on cGAS-mediated signaling pathway. However, transcriptional mechanisms of cGAS gene have remained largely unknown. Here, we cloned the cGAS promoter region and characterized the molecular mechanisms controlling the cGAS transcriptional activity. By a series of 5' deletion and promoter constructions, we showed that the region (-414 to +76 relatives to the transcription start site) was sufficient for promoter activity. Mutation of Sp1 and CREB binding sites in this promoter region led to an apparent reduction of the cGAS promoter activity. Overexpression of Sp1 and CREB could obviously enhance promoter activity, whereas knocking-down of endogenous Sp1 and CREB markedly restrained the cGAS promoter activity. Sp1 and CREB binding to the cGAS promoter region in vivo was verified by Chromatin immunoprecipitation assay. These results pointed out that transcription factors Sp1 and CREB regulate the transcription of the cGAS gene.

Two new flavan glycosides, (2S)-5,7,4'-trihydroxyflavan-7-O-β-D-glucopyranoside and (2S)-5,7,4'-trihydroxyflavan-5-O-β-D-glucopyranoside, and a new neolignan, (7S,8S)-3-methoxyl-3'-O-β-D-glucopyrannosyl-4':8,5':7-diepoxyneolignan-4,9'-diol, were isolated from the leaves of Liquidambar formosana Hance. Their structures were elucidated on the basis of spectroscopic data and chemical evidence.

Transmissible spongiform encephalopathies (TSEs) are prion protein misfolding diseases that involve the accumulation of an abnormal β-sheet-rich prion protein aggregated form (PrP(sc)) of the normal α- helix-rich prion protein (PrP(c)) within the central nervous system (CNS) and other organs. On account of its large size and insolubility properties, characterization of PrP(c) is quite difficult. A soluble intermediate, called PrP(β) or β(o), exhibiting many of the same features as PrP(sc), can be generated using a combination of low pH and/or mild denaturing conditions. Here, we review the current knowledge on the following five issues relevant to the conversion mechanisms of PrP(c) to PrP(sc) : (1) How is the Stability of the Helical Structures in the Native PrP(c) Related to the Primary Structure of the PrP(c) (2) Why the Low pH Solution System is a Ideal Trigger of PrP(c) to PrP(sc) Conversion (3) How are the Structural and Dynamical Characteristics of the α-helixrich Intermediates Determined using NMR Data (4) How are the Premolten (PrP(α4) and PrP(αβ)) and β-Oligomer (PrP(β)) Intermediates Detected and Assayed, and (5) Can the Disordered N-terminal Domain be folded into the Structural Segment? Particularly, Chou's wenxiang diagram (http://en.wikipedia.org/wiki/Wenxiang_diagram) was introduced for providing an intuitive picture. This review may help to further understand the prion protein misfolding mechanism.

Retinopathy of prematurity, a leading cause of visual impairment in low birth-weight infants, remains a crucial therapeutic challenge. Ciliary neurotrophic factor (CNTF) is a promyelinating trophic factor that promotes rod and cone photoreceptor survival and cone outer segment regeneration in the degenerating retina. Ciliary neurotrophic factor expression is regulated by many factors such as all-trans retinoic acid (ATRA). In this study, we found that ATRA increased CNTF expression in mouse retinal pigment epithelial (RPE) cells in a dose- and time-dependent manner, and PKA signaling pathway is necessary for ATRA-induced CNTF upregulation. Furthermore, we showed that ATRA promoted CNTF expression through CREB binding to its promoter region. In addition, CNTF levels were decreased in serum of retinopathy of prematurity children and in retinal tissue of oxygen-induced retinopathy mice. In mouse RPE cells cultured with high oxygen, CNTF expression and secretion were decreased, but could be recovered after treatment with ATRA. In conclusion, our data suggest that ATRA administration upregulates CNTF expression in RPE cells.

Five new oleanane-type triterpenoid saponins, oleiferasaponins D1–D5 (1–5), were isolated from the defatted seeds of Camellia oleifera Abel. Their structures were elucidated by spectroscopic and chemical methods. The cytotoxic activities of compounds 1–5 were evaluated against five human tumor cell lines (HCT-116, HepG2, BGC-823, NCI-H1650, and A2780). Compounds 1–2 exhibited cytotoxic activity against five human cancer cell lines, with IC50 values ranging from 3.31 to 10.23 μM. Compounds 3–5 showed moderate cytotoxic activities toward the tested cell lines.

As a subset of glycosyltransferases, the family of sialyltransferases catalyze transfer of sialic acid (Sia) residues to terminal non-reducing positions on oligosaccharide chains of glycoproteins and glycolipids, utilizing CMP-Neu5Ac as the activated sugar nucleotide donor. In the four known sialyltransferase families (ST3Gal, ST6Gal, ST6GalNAc and ST8Sia), the ST8Sia family catalyzes synthesis of α2, 8-linked sialic/polysialic acid (polySia) chains according to their acceptor specificity. We have determined the 3D structural models of the ST8Sia family members, designated ST8Sia I (1), II(2), IV(4), V(5), and VI(6) using the Phyre2 server. Accuracy of these predicted models are based on the ST8Sia III crystal structure as the calculated template. The common structural features of these models are: (1) Their parallel templates and disulfide bonds are buried within the enzymes and are predominately surrounded by helices; (2) The anti-parallel β-sheets are located at the N-terminal region of the enzymes; (3) The mono-sialytransferases (mono-STs), ST8Sia I and ST8Sia VI, contain only a single pair of disulfide bonds, and there are no anti-parallel β-sheets in ST8Sia VI; (4) The Nterminal region of all of the mono-STs are located some distant away from their core structure; (5) These conformational features show that the 3D structures of the mono-STs are less compact than the two polySTs, ST8Sia II and ST8Sia IV, and the oligo-ST, ST8Sia III. These structural features relate to the catalytic specificity of the monoSTs; (6) In contrast, the more compact structural features of ST8Sia II, ST8Sia IV and ST8Sia III relate to their ability to catalyze the processive synthesis of oligo- (ST8Sia III) and polySia chains (ST8Sia IIamp; ST8Sia IV); (7) Although ST8Sia II, III and IV have similar conformations in their corresponding polysialyltransferase domain (PSTD) and polybasic region (PBR) motifs, the structure of ST8Sia III is less compact than ST8Sia II and ST8Sia IV, and the amino acid components of the several three-residue-loops in the two motifs of ST8Sia III are different from that in ST8Sia II and ST8Sia IV. This is likely the structural basis for why ST8Sia III is an oligoST and not able to polysialylate and; (8) In contrast, essentially all amino acids within the threeresidue- loops in the PSTD of ST8Sia II and ST8Sia IV are highly conserved, and many amino acids in the loops and the helices of these two motifs are critical for NCAM polysialylation, as determined by mutational analysis and confirmed by our recent NMR results. In summary, these new findings provide further insights into the molecular mechanisms underlying polyST-NCAM recognition, polySTpolySia/ oligoSia interactions, and polysialylation of NCAM.

Applying the Internet of Things (IOT) into ecological environmental monitoring is the goal of this paper. There are several advantages of the Internet of Things (IOT) applying in ecological environment monitoring. A hierarchical monitoring system is presented, including system architecture, hardware/software design, information flow and software implementation. In the end, using carbon dioxide gas in the atmosphere for experimental purposes, in data collection and analysis. Experiments showed that this system is capable of monitoring ecologica environment, which orientate the future research of forest ecosystem.

Physiologic relaxation of vascular smooth muscle is induced by the cyclic guanosine monophosphate (cGMP)- dependent protein kinase Iα enzyme (cGKIα), which activates myosin phosphatase (MLCP). This activation process is thought to occur through the interaction involving both N- and C-terminal leucine zipper coiled-coil (LZCC) domains of the kinase enzyme (cGKIα) with the myosin binding subunit (MBS) of MLCP. In this review, I summarize how to define the LZCC domains in both N-terminal cGKIα(1-59) and C-terminal MBS proteins using predictive and experimental methods, how to make a rapid and accurate structure determination of a cGKIα(1-59) molecule using NMR's residual dipolar coupling (RDC) measurements, and how to indentify the existence of a weak protein interaction between N-terminal LZCC domain (cGKIα(1-59)) and a LZCC domain (MBSCT42) within the C-terminal MBS. In addition, the location and orientation of the residues in LZCC proteins can be readily visualized using a novel diagram, the so-called "wenxiang diagram", which is more advantageous than traditional helical wheel diagrams in analyzing LZCC protein structures and their action mechanisms. Using the composed wenxiang diagrams, we have characterized the interaction between cGKIα(1- 59) and another LZCC molecule (MBSCT42), and deduced that the most affected residues of these two LZCC molecules might be at the positions d, a, e and g. These studies and findings are also covered in this review. It is intriguing to see that the successful incorporation of wenxiang diagrams and NMR spectroscopy in the LZCC structural and functional studies may provide some insights into protein-protein interaction mechanisms.

Wenxiang diagram is a new two-dimensional representation that characterizes the disposition of hydrophobic and hydrophilic residues in α-helices. In this research, the hydrophobic and hydrophilic residues of two leucine zipper coiled-coil (LZCC) structural proteins, cGKIα1−59 and MBSCT35 are dispositioned on the wenxiang diagrams according to heptad repeat pattern (abcdefg)n, respectively. Their wenxiang diagrams clearly demonstrate that the residues with same repeat letters are laid on same side of the spiral diagrams, where most hydrophobic residues are positioned at a and d, and most hydrophilic residues are localized on b, c, e, f and g polar position regions. The wenxiang diagrams of a dimetric LZCC can be represented by the combination of two monomeric wenxiang diagrams, and the wenxiang diagrams of the two LZCC (tetramer) complex structures can also be assembled by using two pairs of their wenxiang diagrams. Furthermore, by comparing the wenxiang diagrams of cGKIα1−59 and MBSCT35, the interaction between cGKIα1−59 and MBSCT35 is suggested to be weaker. By analyzing the wenxiang diagram of the cGKIα1−59.·MBSCT42 complex structure, most affected residues of cGKIα1−59 by the interaction with MBSCT42 are proposed at positions d, a, e and g of the LZCC structure. These findings are consistent with our previous NMR results. Incorporating NMR spectroscopy, the wenxiang diagrams of LZCC structures may provide novel insights into the interaction mechanisms between dimeric, trimeric, tetrameric coiled-coil structures., Highlights ► cGKIα1−59·MBSCT35 hexamer complex can be represented by a combined wenxiang diagrams. ► These diagrams characterize the interaction between these two LZCC structures. ► The findings by using wenxiang diagram method are consistent with the NMR results.

The formation of phosphorous surface inverse segregation (SIS) in twin-roll cast strips of low-carbon steels was studied. High phosphorous strips were fabricated by using a pilot twin-roll strip caster and a melt/substrate contacting apparatus, respectively. Solidification structures of strips were observed and analyzed, and phosphorus distributions along longitudinal sections of strips were investigated and discussed. The results showed that solidification structures of all strips were columnar grains, either integrated or coarse in the strip made by the melt/substrate contacting apparatus or damaged in some degree in cast strips; and that during cast strip solidification, enrichment of phosphorus occurred between columnar grains, and the average phosphorus concentration near the surface in the strip with 0. 15% of phosphorus was measured to be about 0. 27% which was obviously higher than that in the bulk.

Nitric oxide and nitrovasodilators induce vascular smooth muscle cell relaxation in part by cGMP-dependent protein kinase I (PKG-Ialpha)-mediated activation of myosin phosphatase (MLCP). Mechanistically it has been proposed that protein-protein interactions between the N-terminal leucine zipper (LZ) domain of PKG-Ialpha ((PKG-Ialpha(1-59)) and the LZ and/or coiled coil (CC) domain of the myosin binding subunit (MBS) of MLCP are localized in the C terminus of MBS. Although recent studies have supported these interactions, the critical amino acids responsible for these interactions have not been identified. Here we present structural and biophysical data identifying that the LZ domain of PKG-Ialpha(1-59) interacts with a well defined 42-residue CC motif (MBS(CT42)) within the C terminus of MBS. Using glutathione S-transferase pulldown experiments, chemical cross-linking, size exclusion chromatography, circular dichroism, and isothermal titration calorimetry we identified a weak dimer-dimer interaction between PKG-Ialpha(1-59) and this C-terminal CC domain of MBS. The K(d) of this non-covalent complex is 178.0+/-1.5 microm. Furthermore our (1)H-(15)N heteronuclear single quantum correlation NMR data illustrate that this interaction is mediated by several PKG-Ialpha residues that are on the a, d, e, and g hydrophobic and electrostatic interface of the C-terminal heptad layers 2, 4, and 5 of PKG-Ialpha. Taken together these data support a role for the LZ domain of PKG-Ialpha and the CC domain of MBS in this requisite contractile complex.

All residues in an alpha helix can be characterized and dispositioned on a 2D the wenxiang diagram, which possesses the following features: (1) the relative locations of the amino acids in the α-helix can be clearly displayed regardless how long it is; (2) direction of an alphahelix can be indicated; and (3) more information regarding each of the constituent amino acid residues in an alpha helix. Owing to its intuitionism and easy visibility, wenxiang diagrams have had an immense influence on our understanding of protein structure, protein-protein interactions, and the effect of helical structural stability on protein conformational transitions. In this review, we summarize two recent applications of wenxiang diagrams incorporating NMR spectroscopy in the researches of the coiled-coil protein interactions related to the regulation of contraction or relaxation states of vascular smooth muscle cells, and the effects of α-helical stability on the protein misfolding in prion disease, in hopes that the gained valuable information through these studies can stimulate more and more widely applications of wenxiang diagrams in structural biology.

Four new triterpenoids which were identifed as 2α,3β,6β,19α-tetrahydroxy- oleanolic acid 28-O-β-D-glucopyranoside (1), 2-O-β-D-glucopyranosyloxy-3α,19α-di-hydroxyoleanolic acid (2), 2-O-β-D-glucopyranosyloxy-3α,19α-dihydroxyursolic acid (3), 2α,3α,6β,19α-tetrahydroxyursolic acid 28-O-β-D-glucopyranoside (4), were isolated from the aerial parts of Callicarpa kwangtungensis together with three known triterpenoids identified as 2α,3β,21β-trihydroxyursolic acid 28-O-β-D-glucopyranoside (5), 2α,3α,19α,23-tetrahydroxyoleanolic acid 28-O-β-D-glucopyranoside (6), 2α,3α,19α,23-tetrahydroxyursolic acid 28-O-β-D-glucopyranoside (7). Their structures were elucidated by the combination of mass spectrometry (MS), one and two-dimensional NMR experiments.

The 13-amino acid glycopeptide tx5a (Gla-Cys-Cys-Gla-Asp-Gly-Trp*-Cys-Cys-Thr*-Ala-Ala-Hyp-OH, where Trp* = 6-bromotryptophan and Thr* = Gal-GalNAc-threonine), isolated from Conus textile, causes hyperactivity and spasticity when injected intracerebral ventricularly into mice. It contains nine post-translationally modified residues: four cysteine residues, two gamma-carboxyglutamic acid residues, and one residue each of 6-bromotryptophan, 4-trans-hydroxyproline and glycosylated threonine. The chemical nature of each of these has been determined with the exception of the glycan linkage pattern on threonine and the stereochemistry of the 6-bromotryptophan residue. Previous investigations have demonstrated that tx5a contains a disaccharide composed of N-acetylgalactosamine (GalNAc) and galactose (Gal), but the interresidue linkage was not characterized. We hypothesized that tx5a contained the T-antigen, beta-D-Gal-(1-->3)-alpha-D-GalNAc, one of the most common O-linked glycan structures, identified previously in another Conus glycopeptide, contalukin-G. We therefore utilized the peracetylated form of this glycan attached to Fmoc-threonine in an attempted synthesis. While the result-ing synthetic peptide (Gla-Cys-Cys-Gla-Asp-Gly-Trp*-Cys-Cys-Thr*-Ala-Ala-Hyp-OH, where Trp* =6-bromotryptophan and Thr* = beta-D-Gal-(1-->3)-alpha-D-GalNAc-threonine) and the native peptide had almost identical mass spectra, a comparison of their RP-HPLC chromatograms suggested that the two forms were not identical. Two-dimensional H-1 homonuclear and C-13-H-1 heteronuclear NMR spectroscopy of native tx5a isolated from Conus textile was then used to determine that the glycan present on tx5a indeed is not the aforementioned T-antigen, but rather alpha-D-Gal-(1-->3)-alpha-D-GalNAc. (Less)

Earlier NMR studies showed that the polyisoprenols (PIs) dolichol (C95), dolichylphosphate (C95-P) and undecaprenylphosphate (C55-P) could alter membrane structure by inducing in the lamellar phospholipid (PL) bilayer a nonlamellar or hexagonal (Hex II) structure. The destabilizing effect of C95 and C95-P on host fatty acyl chains was supported by small angle X-ray diffraction and freeze-fracture electron microscopy. Our present 1H- and 31P-NMR studies show that the addition of a polyisoprenol recognition sequence (PIRS) peptide to nonlamellar membranes induced by the PIs can reverse the hexagonal structure phase back to a lamellar structure. This finding shows that the PI:PIRS docking complex can modulate the polymorphic phase transitions in PL membranes, a finding that may help us better understand how glycosyl carrier-linked sugar chains may traverse membranes. Using an energy-minimized molecular modeling approach, we also determined that the long axis of C95 in phosphatidylcholine (PC) membranes is oriented approximately parallel to the interface of the lipid bilayer, and that the head and tail groups are positioned near the bilayer interior. In contrast, the phosphate head group of C95-P is anchored at the PC bilayer, and the angle between the long axis of C95-P and the bilayer interface is about 758, giving rise to a preferred conformation more perpendicular to the plane of the bilayer. Molecular modeling calculations further revealed that up to five PIRS peptides can bind cooperatively to a single PI molecule, and this tethered structure has the potential to form a membrane channel. If such a channel were to exist in biological membranes, it could be of functional importance in glycoconjugate translocation, a finding that has not been previously reported.

The major heat shock protein, Hsp70, can protect against cell death by directly interfering with mitochondrial apoptosis pathways. However, Hsp70 also sensitizes cells to certain apoptotic stimuli like TNF. Little is known about how Hsp70 enhances apoptosis. We demonstrate here that Hsp70 promotes TNF killing by specifically binding the coiled-coil domain of I kappa B kinase gamma (IKK gamma) to inhibit IKK activity and consequently inhibit NF-kappa B-dependent antiapoptotic gene induction. An IKK gamma mutant, which interacts with Hsp70, competitively inhibits the Hsp70-IKK gamma interaction and relieves heat-mediated NF-kappa B suppression. Depletion of Hsp70 expression with RNA interference rescues TNF-mediated cell death. Although TNF may or may not be sufficient to trigger apoptosis on its own, TNF-triggered apoptosis was initiated or made worse when Hsp70 expression increased to high levels to disrupt NF-kappa B signaling. These results provide significant novel insights into the molecular mechanism for the pro-apoptotic behavior of Hsp70 in death-receptor-mediated cell death.

A new 3-(3,4-methylenedioxyphenyl)-propane-1,2-diol glycoside, named cinnamomdiol A ( 1 ), together with two known compounds, 3-(3,4-methylenedioxyphenyl)-propane-1,2-diol ( 2 ) and taxifolin ( 3 ), was isolated from the roots of Cinnamomum camphora . Their structures were determined on the basis of spectroscopic evidences. Compounds 2 and 3 were isolated from the title plant for the first time.

Three new labdane-type diterpene glycosides, 15,18-di-O-β-d-glucopyranosyl-13(E)-ent-labda-7(8),13(14)-diene-3β,15,18-triol (1), 15,18-di-O-β-d-glucopyranosyl-13(E)-ent-labda-8(9),13(14)-diene-3β,15,18-triol (2), and 15-O-β-d-apiofuranosyl-(1→2)-β-d-glucopyranosyl-18-O-β-d-glucopyranosyl-13(E)-ent-labda-8(9),13(14)-diene-3β,15,18-triol (3), were isolated from the fruits of Rubus chingii. Their structures were elucidated on the basis of spectroscopic data and chemical methods. The cytotoxic activities of compounds 1-3 were evaluated against five human tumor cell lines (HCT-8, BGC-823, A549, and A2780). Compounds 3 showed cytotoxic activity against A549 with an IC50 value of 2.32μM.

Synthesis of α2,8-polysialic acid (polySia) glycans are catalyzed by two highly homologous mammalian polysialyltransferases (polySTs), ST8Sia II (STX) and ST8Sia IV (PST), which are two members of the ST8Sia gene family of sialytransferases. During polysialylation, both STX and PST catalyze the transfer of multiple Sia residues from the activated sugar nucleotide precursor, CMP-Neu5Ac (Sia), to terminal Sia residues on N- and Olinked oligosaccharide chains on acceptor glycoproteins, including the neural cell adhesion molecule (NCAM), which is the major carrier protein of polySia. Based on our new findings and previously published studies, this review summarizes the present concepts regarding the molecular mechanism underlying regulation of protein-specific polysialylation of NCAM that includes the following: (1) Determination of the catalytic domains and specific regions within ST8Sia IV for recognizing and catalyzing the efficient polysialylation of NCAM; (2) Identification of key amino acid residues within the PSTD motif of ST8Sia IV that are essential for polysialylation; (3) Verification of key amino acids in the PBR domain of ST8Sia IV required for NCAM-specific polysialylation; and (4) a 3D conformational study of ST8Sia IV based on the Phyre2 server to discover the relationship between the structure and its functional domains of the polyST. Based on these results, our 3D model of ST8Sia IV was used to identify and characterize the catalytic domains and amino acid residues critical for catalyzing polysialylation, and have provided new structural information for supporting a detailed mechanism of polyST-NCAM interaction required for polysialylation of NCAM, findings that have not been previously reported.

A novel phenylpropanoid glycoside, Callicarposide A has been isolated from the aerial parts of Callicarpa kwangtungensis Chun. The chemical structure is elucidated on the basis of spectral analysis. (C) 2009 Teng Fei Ji. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

A new bidesmoside triterpenoid saponin, named stauntoside C1 (1) has been isolated from Stauntonia chinensis. Its structure was established by means of spectral and chemical methods.

A recent report by Bahar et al. [(1997), Proteins 29, 172-185] indicates that the coupling effects among different amino acid components as originally formulated by K. C. Chou [(1995), Proteins 21, 319-344] are important for improving the prediction of protein structural classes. These authors have further proposed a compact lattice model to illuminate the physical insight contained in the component-coupled algorithm. However, a completely opposite result was concluded by Eisenhaber et al. [(1996), Proteins 25, 169 179], using a different dataset constructed according to their definition. To address such an intriguing controversy, tests were conducted by various approaches for the datasets from an objective database, the SCOP database [Murzin et al. (1995), J. Mol. Biol. 247, 536-540]. The results obtained by both self-consistency and jackknife tests indicate that the overall rates of correct prediction by the algorithm incorporating the coupling effect among different amino acid components are significantly higher than those by the algorithms without counting such an effect. This is fully consistent with the physical reality that the folding of a protein is the result of a collective interaction among its constituent amino acid residues, and hence the coupling effects of different amino acid components must be incorporated in order to improve the prediction quality. It was found by a revisiting the calculation procedures by Eisenhaber et al. that there was a conceptual mistake in constructing the structural class datasets and a systematic mistake in applying the component-coupled algorithm. These findings are informative for understanding and utilizing the component-coupled algorithm to study the structural classes of proteins.

All-trans retinoic acid (ATRA) is an active metabolite of Vitamin A, it shows protective effects on asthma, including maintains airway epithelial integrity, inhibits asthma effector cells differentiation, modulates immune response, et al. However, the promoting effect of ATRA on Th2 response has restricted the clinical application of ATRA in asthma treatment. ORMDL3 is a candidate gene of childhood onset asthma, and high-transcript of ORMDL3 is associated with the development of asthma. Here we show that ATRA increases ORMDL3 production in vitro via inducing PKA-dependent CREB phosphorylation which in turn binds to the CRE element in promoter region of ORMDL3 and initiates ORMDL3 transcription. This finding is in consistent with the previous reports that ATRA could regulate target genes without the presence of retinoic acid response element (RARE) in promoter region but through other signals such as PKA/CREB. Nevertheless, in the present study, the traditional signal pathway of ATRA, retinoic acid receptor (RAR) signal transduction pathway, indirectly modulated ORMDL3 expression. RAR-α agonist (Am-80) increased ORMDL3 production even though there was no RARE in ORMDL3 promoter, introns or 3′-downstream region. Besides, the signal of RAR might differ from that of ATRA since Am-80 failed to induce CREB activation. In conclusion, our data indicate that ATRA facilitates ORMDL3 production probable through PKA/CREB, and this may be a starting point for more detailed mechanism researches on ATRA and asthma.

A simple, sensitive and specific UHPLC-MS/MS method for quantification of plantagoguanidinic acid (PGA) in rat plasma was applied to investigate the pharmacokinetic behavior in vivo, using protopine as internal standard. The chromatography was separated on a Phenomenex® Luna-C18 column (2.1 × 150 mm, 3.0 μm) within 7.0 min using a mobile phase consisting of acetonitrile-0.1% formic acid solution under gradient elution at a flow rate of 0.4 mL/min. Prepared samples were monitored by multiple reaction monitoring mode, with the target fragmentions m/z 226.2 → 84.2 for PGA and m/z 354.2 → 188.9 for IS in positive electrospray ionization. The calibration curve of PGA was linear throughout the range 1-1000 ng/mL (r = 0.9962). The lower limit of quantitation in plasma for PGA was 0.1 ng/mL, and the recovery was >88.6%. Intra- and interday accuracy ranged from -8.6 to 4.9%. Furthermore, this validated method was successfully used for a pre-clinical pharmacokinetic study of PGA at a single dose of 20 and 5 mg/kg in rats via oral and intravenous administration. The study showed that PGA was absorpted rapidly and eliminated gradually with a greater absolute oral bioavailability of 70.1% in rats.

Prions are believed to spontaneously convert from a native, monomeric highly helical form (called PrP c) to a largely β-sheet-rich, multimeric and insoluble aggregate (called PrP sc). Because of its large size and insolubility, biophysical characterization of PrP sc has been difficult, and there are several contradictory or incomplete models of the PrP sc structure. A β-sheet-rich, soluble intermediate, called PrP β, exhibits many of the same features as PrP sc and can be generated using a combination of low pH and/or mild denaturing conditions. Studies of the PrP c to PrP β conversion process and of PrP β folding intermediates may provide insights into the structure of PrP sc. Using a truncated, recombinant version of Syrian hamster PrP β (shPrP(90-232)), we used NMR spectroscopy, in combination with other biophysical techniques (circular dichroism, dynamic light scattering, electron microscopy, fluorescence spectroscopy, mass spectrometry, and proteinase K digestion), to characterize the pH-driven PrP c to PrP β conversion process in detail. Our results show that below pH 2.8 the protein oligomerizes and conversion to the β-rich structure is initiated. At pH 1.7 and above, the oligomeric protein can recover its native monomeric state through dialysis to pH 5.2. However, when conversion is completed at pH 1.0, the large oligomer "locks down" irreversibly into a stable, β-rich form. At pH values above 3.0, the protein is amenable to NMR investigation. Chemical shift perturbations, NOE, amide line width, and T 2 measurements implicate the putative "amylome motif" region, "NNQNNF" as the region most involved in the initial helix-to-β conversion phase. We also found that acid-induced PrP β oligomers could be converted to fibrils without the use of chaotropic denaturants. The latter finding represents one of the first examples wherein physiologically accessible conditions (i.e., only low pH) were used to achieve PrP conversion and fibril formation. © 2010 American Chemical Society.

A new bidesmoside triterpenoid saponin, named stauntoside C1 (1), along with three known saponins (2-4) was isolated from Stauntonia chinensis DC. (Lardizabalaceae). Their structures were established by means of spectral and chemical methods as 3-O-beta-D-xylopyranosyl-(1 --2)-O-beta-D-xylopyranosyl-(1 --3)-O-alpha-L-rhamnopyranosyl-(1 --2)-alpha-L-arabinopyranosyl oleanolic acid 28-O-alpha-L-rhamnopyranosyl-(1 --4)-beta-D-glucopyranosyl-(1 --6)-beta-D-glucopyranosyl ester (1), scabiosaponin E (2), sieboldianoside B (3), and kizutasaponin K(12) (4).