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Rheumatoid arthritis (RA) is an autoimmune inflammatory disease that leads to cartilage damage, joint destruction and bone erosions. Serological analysis is one of the most important tools for diagnosis of RA. The aims of studies were the synthesis of an amino-acid library of epitope CHHLDKSIKEDVQFADSRI corresponding to the flap region of H. pylori urease and investigation recognition by serum antibodies from one rheumatoid arthritis patient (RAP) and one volunteer blood donor (VBD) tested by two semi-quantitative methods. In this study we compared two immunoblot variants for estimation of antibodies recognizing five synthetic peptides corresponding to the urease flap region sequence from different organisms. One immunoblot variant was a classic dot-blot using HRP-conjugated anti-human antibodies, where the level of bound immunoglobulins was estimated by digitization of color formed by reaction with secondary antibody. The second immunoblot variant was based on fluorescein-conjugated anti human antibodies. Both semi-quantitative methods were effective for evaluation of antibodies, and their advantages and disadvantages are discussed. To identify the amino-acid residues critical for reaction with antibodies, an amino-acid scan of the complete sequence of the flap region from Helicobacter pylori urease (epitope BK-61B) was conducted. Each sub-library (1–19) contained 19 peptides, each with different amino acids (a–w) at defined positions. All components of the library were synthesized using a divergent strategy. Patterns of serological reaction with the peptide library were unique for each serum sample from an RA patient or control blood donor. The amino-acid residues in epitope BK-61B necessary for strong reaction with antibodies and preventing reaction with antibodies were identified.

International audience; Metal chelates targeted to amyloid peptides are widely explored as diagnostic tools or therapeutic agents. The attachment of a metal complex to amyloid recognition units typically leads to a decrease in peptide affinity. We show here that by separating a macrocyclic GdL chelate and a PiB targeting unit with a long hydrophobic C10 linker, it is possible to attain nanomolar affinities for both Aβ 1‐40 ( K d = 4.4 nM) and amylin ( K d = 4.5 nM), implicated respectively in Alzheimer’s disease and diabetes. The Scatchard analysis of surface plasmon resonance data obtained for a series of amphiphilic, PiB derivative GdL complexes indicate that their Aβ 1‐40 or amylin binding affinity varies with their concentration, thus micellar aggregation state. The GdL chelates also affect peptide aggregation kinetics, as probed by thioflavin‐T fluorescence assays. A 2D NMR study allowed identifying that the hydrophilic region of Aβ 1‐40 is involved in the interaction between the monomer peptide and the Gd 3+ complex. Finally, ex vivo biodistribution experiments were conducted in healthy mice by using 111 In labelled analogues. Their pancreatic uptake, ~3%ID/g, is promising to envisage amylin imaging in diabetic animals.

Lysozyme (1,4-β-N-acetylmuramidase) is commonly applied in the food, medical, and pharmaceutical industries. In this study, we tested a novel application of fluorescein-modified lysozyme (using carboxyfluorescein with a triazine-based coupling reagent) as a new tool for the detection of Gram-positive soil bacteria. The results, obtained by cultivation methods, fluorescence analysis, and laser interferometry, showed that, after optimization, fluorescein-modified lysozyme could be used to evaluate the prevalence of Gram-positive bacteria essential in bioremediation of soils with low pH, such as those degraded by sulfur.

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease. Early diagnosis can prevent joint erosion. However, available biomarkers do not always allow for clear distinction between RA and non-RA individuals. It has become known that bacteria/viruses are among the environmental triggers that initiate RA via multiple molecular mechanisms. Thus, to better understand the role of bacteria in RA, we synthetized 6 peptidomimetics of bacterial ureases' flap region. These peptides were then used to distinguish RA patients from healthy people sera by immunoblotting. Most patients' sera were bound to peptidomimetic characteristic for Enterobacter sp. and Klebsiella sp. flap urease. We also found similarities between peptidomimetic sequence and human proteins connected with RA. This pilot study suggests that bacteria may trigger RA via mechanism of molecular mimicry of urease to host proteins and ureases flap peptidomimetics may be potential candidate as a new additional diagnostic test.

A collection of N-triazinylammonium sulfonates, designed according to the concept of “superactive esters”, was obtained by treatment of ammonium sulfonates with 2-chloro-4,6-dimethoxy-1,3,5-triazine. The structure of the tertiary amine as well as sulfonate anion influenced their reactivity and stability in N,N-dimethylformamide (DMF) solution. The reagents were successfully used in solution- and solid-phase synthesis of Z-, Boc-, and Fmoc-protected peptides containing natural and unnatural sterically hindered amino acids as well as in [2+1] fragment condensation approaches, yielding the final products in 80–100 % yield and high optical purity. In manual SPPS of the [Aib]2[Aib]4-enkephalin analogue and the ACP(65–74) peptide fragment VQAAIDYINEG, several sulfonates yielded peptides significantly faster than TBTU or HATU. Comparative analyses demonstrated that 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium 4-toluenesulfonate was the most versatile reagent in a wide range of coupling procedures.

Overlapping decapeptide fragments of H. pylori urease subunit A (UreA) were synthesized and tested with polyclonal antibodies against Canavalia ensiformis (Jack bean) urease. The linear epitopes of UreA identified using the dot blot method were then examined using epitope mapping. For this purpose, series of overlapping fragments of UreA, frameshifted ± four amino acid residues were synthesized. Most of the UreA epitopes which reacted with the Jack bean urease polyclonal antibodies had been recognized in previous studies by monoclonal antibodies against H. pylori urease. Fragments 11 - 24, 21 - 33, and 31 - 42 were able to interact with the Jack bean urease antibodies, giving stable immunological complexes. However, the lack of recognition by these antibodies of all the components in the peptide map strongly suggests that a non-continuous (nonlinear) epitope is located on the N-terminal domain of UreA.

Advantages offered by immobilization of any component of the reacting system are rewarding all additional efforts and the cost of the support. The majority of the methods reported have been based on the principles of solid phase organic synthesis (SPOS) in which the substrate is attached to the polymer support and excesses of reactants and reagents used to drive each synthetic step to completion. Then simple filtration affords a polymer bound product. While this approach is undoubtedly effective, there are a number of drawbacks which include the requirement for additional chemical steps to attach starting material, to develop synthetic methodology for the solid phase and to cleave products. More recently, solution phase methods, which circumvent these difficulties, have been introduced as alternatives to SPOS. These allow the use of excess of reagents followed by sequestrating either the product or excess reagents and byproducts from the reaction mixture using an insoluble functionalized polymer. Isolation and purification can then be achieved by simple filtration and evaporation.