Structure of the Anti-C60 Fullerene Antibody Fab Fragment: Structural Determinants of Fullerene Binding.

The structure of the anti-C60 fullerene antibody Fab fragment (FabC60) was solved by X-ray crystallography. The computer-aided docking of C60 into the antigen-binding pocket of FabC60 showed that binding of C60 to FabC60 is governed by the enthalpy and entropy; namely, by π-π stacking interactions with aromatic residues of the antigen-binding site and reduction of the solvent-accessible area of the hydrophobic surface of C60. A fragment of the mobile CDR H3 loop located on the surface of FabC60 interferes with C60 binding in the antigen-binding site, thereby resulting in low antibody affinity for C60. The structure of apo-FabC60 has been deposited with pdbid 6H3H.

Development of a multicomponent immunochromatographic test system for the detection of fluoroquinolone and amphenicol antibiotics in dairy products.

BACKGROUND: Ciprofloxacin (CIP) and chloramphenicol (CAP) are relevant antibiotics of the fluoroquinolone (FQ) and amphenicol (AP) groups, respectively, widely used in veterinary practice and they contaminate agricultural products. In this study, a rapid and sensitive immunochromatographic assay (ICA) was developed for simultaneous detection of CIP and CAP in dairy products. The ICA was carried out in a direct competitive format using gold nanoparticles as a label. RESULTS: The ICA developed here allowed for the detection of CIP and CAP in Triton X-100-containing buffered saline (PBST) within 15 min with instrumental detection limits of 20 pg mL-1 and 0.5 ng mL-1 , respectively, and with a visual detection limit of 5 ng mL-1 for both antibiotics. The ICA showed cross-reactivity (69-160%) to 19 antibiotics in the FQ group and no cross-reactivity (<0.1%) to 2 antibiotics of the AP group. The ICA allowed detection of CIP and CAP in a panel of dairy products by employing a simple procedure of preliminary sample preparation. The detection limits for the two antibiotics were the same as in PBST. The analytical recoveries of CIP and CAP in dairy products ranged from 83% to 120%. CONCLUSION: The analytical characteristics of the test system allow its use for the detection of antibiotics in milk and dairy products during all steps of production. © 2019 Society of Chemical Industry.

Analytical Application of Lectins.

This review is devoted to the analytical application of carbohydrate-binding proteins called lectins. The nature of lectins and the regularities of their specificity with respect to simple sugars and complex carbohydrate-containing biomolecules are discussed. The main areas of the modern analytical application of lectins are described. Lectin-affinity chromatography, histo- and cytochemical approaches, lectin blotting, microarray, and biosensor technologies as well as microplate analysis are considered in detail. Data on the use of lectins for the detection of cells and microorganisms as well as the study of protein glycosylation are summarized. The large potential of lectins as components of analytical systems used for the identification of glycans and the characteristics of their structure are substantiated.

Development of liposome immune lysis assay for the herbicide atrazine.

A homogeneous complement-mediated liposome immune lysis assay (LILA) was developed for determination of the herbicide atrazine. To dispose the antigen on the surface of lipid bilayer the atrazine was conjugated to a dimirystoylphosphatidylethanolamine (DMPE) carrier. Calcein was compared with sulforhodamine 101 as a fluorophore label for entrapping into the antigen-sensitized liposomes. The liposomes were incubated with rabbit anti-atrazine antibodies in the presence of guinea pig complement. Formation of the antigen-antibody complexes on the liposomal surface initiated the lytic action of the complement. As free competing atrazine inhibited the lytic reaction, the amount of calcein released was inversely proportional to the atrazine content in the probe. Concentration and kinetic dependences of the immunoassay were characterized to reach its maximal sensitivity. The developed assay allows detecting atrazine in concentrations up to 0.13 ng mL(-1) in the sample (0.04 ng mL(-1) in the final reaction mixture). The named sensitivity is two orders higher than those for the microplate enzyme-linked immunosorbent assay (ELISA) with the same antibodies which allows us to recommend LILA for environmental monitoring.