Peptide-protein complex from cattle sclera: Structural aspects and chaperone activity.

The influence of temperature and chaotropic agents on the spatial organization of the peptide-protein complex isolated from cattle sclera at the level of secondary structure was studied by UV, CD spectroscopy, and dynamic light scattering. It is shown that this complex has high conformational thermostability. The point of conformational thermal transition (65 °C) was determined, after which the peptide-protein complex passes into a denatured stable state.

Extraction of residual heavy metals from commercial chitosan and approach to preparation of oligochitosan hydrochloride.

For biomedical applications, chitosan and oligochitosan must be appropriately characterized and meet pharmacological requirements in terms of contamination by residual heavy metals. In this work, a series of commercial chitosans was analyzed by ICP-MS method, and high concentration of Fe (44-382 ppm), Cr (3.1-35.

Consequences of chitosan decomposition by nitrous acid: Approach to non-branched oligochitosan oxime.

It is well known that chitosan degradation by nitrous acid leads to oligochitosan (oligoCHI-ahm) bearing reactive 2,5-anhydromannose (3,4-dihydroxy-5-hydroxymethyl-tetrahydrofuran-2-aldehyde) units at the new reducing ends of macromolecules. Standard protocol requires reduction of oligoCHI-ahm with NaBH to corresponding oligoCHI-hml bearing unreactive hydroxymethyl group instead of reactive aldehyde group. For the first time, HP SEC as well as UV and CD spectroscopy methods have revealed that the reduction leads to an indefinite side modification and the formation of a branched oligoCHI-hml with increased molecular weight.

Influence of glucosamine on oligochitosan solubility and antibacterial activity.

Light scattering studies indicate that oligochitosan (short-chain chitosan) solutions contain aggregates at pH values below the critical pH of phase separation, while at or above this point the gel phase coexists with the aggregate solution. This work demonstrates for the first time that the presence of D-glucosamine in an oligochitosan solution shifts the critical pH to a higher value and improves the oligochitosan antibacterial activity against Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermis in neutral and slightly alkaline aqueous media. By comparing the results of light scattering studies and antimicrobial assays one can conclude that the antimicrobial activity of oligochitosan is dependent on its unimolecular form, not its supramolecular structures.

Polyelectrolyte thromboresistant affinity coatings for modification of devices contacting blood.

The modification of hydrophobic polyethylene/polystyrene surfaces of medical devices with bilayer/multilayer coatings (BCs/MCs) based on polyelectrolyte complexes (PEC) of modified poly(N-vinylpyrrolidone-co-maleic acid) copolymer (VPMA) with chitosan, amphiphilic chitosan, or albumin was studied. The VPMA contained l-Lysine as affinity ligand for plasminogen attached through alpha-amino group. The surface properties and chemical composition of the surfaces investigated were analyzed, using sessile-drop water contact angle measurements, attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM).

The mechanism of alpha-proton isotope exchange in amino acids catalysed by tyrosine phenol-lyase. What is the role of quinonoid intermediates?

To shed light on the mechanism of isotopic exchange of alpha-protons in amino acids catalyzed by pyridoxal phosphate (PLP)-dependent enzymes, we studied the kinetics of quinonoid intermediate formation for the reactions of tyrosine phenol-lyase with L-phenylalanine, L-methionine, and their alpha-deuterated analogues in D2O, and we compared the results with the rates of the isotopic exchange under the same conditions. We have found that, in the L-phenylalanine reaction, the internal return of the alpha-proton is operative, and allowing for its effect, the exchange rate is accounted for satisfactorily. Surprisingly, for the reaction with L-methionine, the enzymatic isotope exchange went much faster than might be predicted from the kinetic data for quinonoid intermediate formation.

Use of the affinity chromatography principle in creating new thromboresistant materials.

The principle of affinity chromatography was used for preparation of thromboresistant bilayer coatings. The outer biospecific layer containing epsilon-aminocaproic acid residues (from 2.2 up to 5.