[The composition of immune sera against Neisseria meningitidis studied by high-performance liquid chromatography]. / Izuchenie sostava immunnykh syvorotok protiv Neisseria meningitidis metodom vysokoéffektivnoi zhidkostnoi khromatografii.

The comparative study of the composition of immune rabbit sera to N. meningitidis, as well as nonimmune sera, has been made by the methods of HPLC and radial immunodiffusion. The quantitative evaluation of the main serum proteins by the two methods has shown the coincidence of the results yielded by these methods. To study the total level of IgM and IgG in the sera under study, a simple and rapid HPLC technique is proposed. The study of the stability of sera during storage (at 4-6 degrees C) has revealed that immune sera show greater stability during storage under such conditions in comparison with sera obtained from nonimmune animals.

[The role of the tryptophan-62 residue in the structure and function of lysozyme]. / O roli ostatka triptofana-62 v strukture i funktsii lizotsima

The thermostability and thermodinamics of formation of the enzyme-substrate complex of two oxidation products of chicken egg lysozyme with the tryptophane-62 residue modified to N'-formylkinurenine (with 2.5% activity) and kinurenine (with 27.5% activity) have been studied. In thermostability and pH effect on the substrate binding the lysozyme oxidation products do not differ from native lysozyme. The data obtained and thermodynamical characteristics of the enzyme-substrate complex formation suggest that the chemical nature of the 62 residue does not significantly affect the conformational properties of lysozyme, however, having a strongly pronounced effect on the binding of substrate and hence the total enzyme activity.

[Selectivity of lysozyme oxidation by singlet oxygen]. / O selektivnosti okisleniia lizotsima singletnym kislorodom.

Peptide analysis of tryptic hydrolysates of two lysozyme forms derived from oxidation of lysozyme with singlet oxygen shows that Trp-62, located at the active site, is destroyed. This is confirmed by the protective effect of the substrate (chitin), whose presense practically prevents the oxidation. A possibility of oxidating different tryptophan residues is discussed from the view-point of their availability to the reagent.

[Nature of tryptophan photooxidation products in lysozyme in the presence of methylene blue]. / O kharatere produktov fotookisleniia triptofana v lizotsime v prisutstvii metilenovoi sini

One out of six trytophan residues in two lysozyme modification, obtained under lysozyme photooxidation in the presence of methylene blue, is found to be oxidized to N'-formylkinurenine (in one modification) and to kinurenine (in the other modification). The transition of one modification into another via detaching of N'-formyl group by soft acid hydrolysis has shown that one and the same tryptophan residue is oxidized in both products, Possible mechanism of tryptophan oxidation to the products mentioned is discu-sed on the basis of the hypothesis on signlet mechanism of lysozyme photooxidation in the presence of methylene blue.