[Fractionation of a chalone-containing substance from Ehrlich's ascites tumor using high pressure chromatography]. / Fraktsionirovanie keilonsoderzhashchego preparata iz astsitnoi opukholi érlikha s pomoshch'iu khromatografii vysodogo davleniia.

The effect of various fractions of chalone--containing preparation from ascyte Ehrlich's tumour obtained by high performance liquid chromatography (HPLC) on mitotic activity and DNA synthesis in the tumour has been studied. After filtration the division of active chalone component which inhibits entering cells into M-phase and S-phase took place. The component inhibiting DNA synthesis eluated with G1-chalone.

[Oxidative modification of cytochrome P-450 during its function. I. Comparative study of the inactivation of cytochrome P-450 LM2 in various systems]. / Okislitel'naia modifikatsiia tsitokhroma P-450 pri ego rabote. I. Sravnitel'noe issledovanie inaktivatsii tsitokhroma P-450 LM2 v razlichnykh sistemakh.

The changes in the content of purified isolated cytochrome P-450 LM2 under the action of hydrogen peroxide and during its operation in a soluble reconstituted system were studied. It was found that cytochrome P-450 LM2 inactivation by hydrogen peroxide is accompanied by a decrease in the hemoprotein activity, loss of heme, oxidation of SH-groups and changes in the oligomeric state of the enzyme. There were some differences in the mechanisms of cytochrome P-450 LM2 inactivation under the action of H2O2 and during catalysis.

[Oxidative modification of cytochrome P-450 during its function. II. Study of the mechanism of cytochrome P-450 LM2 inactivation in a soluble reconstructed monooxygenase system]. / Okislitel'naia modifikatsiia tsitokhorma P-450 pri ego rabote. II. Issledovanie mekhanizma inaktivatsii tsitokhroma P-450 LM2 v rastvorimoi rekonstruirovannoi monooksigenaznoi sisteme.

Inactivation of cytochrome P-450 LM2 induced by hydrogen peroxide formed in the active site of the enzyme was studied. Catalase did not protect cytochrome P-450 LM2 from inactivation during its operation in a soluble reconstituted system. The hemoprotein inactivation in this system was found to depend on the ratio of hemo- to flavoproteins. It was demonstrated that cytochrome P-450 LM2 inactivation during catalysis is accompanied by cleavage of the hemoprotein molecule. It is probable that this fact plays a key role in regulation of enzyme decay.

[Structural organization and localization of cytochromes P450 in the membrane]. / Strukturnaia organizatsiia i raspolozhenie tsitokhromov P450 v membrane.

The secondary structure prediction of 19 microsomal cytochrome P-450s from two different families was made based on their amino acid sequences. It was shown that there is a structural similarity between the heme-binding sites of these enzymes and the bacterial P-450cam. An average predicted secondary structure of cytochrome P-450 proteins with 70% accuracy contains about 46% alpha-helices, 12% beta-strands, 9% beta-turns and 33% random coil. In the region of the 35-120 residues in microsomal P-450s two adjacent beta alpha beta-units (the Rossmann domain) were recognized, which may interact with the NADPH-cytochrome P-450 reductase. Using the procedure of identification of hydrophobic and membrane-associated alpha-helical segments of 23 cytochromes, only one N-terminal transmembrane anchor was predicted. Also the heme-binding site perhaps includes surface-bound helix. A model of vertebrate microsomal P-450s is proposed. That is an amphypathic membrane protein located on the cytoplasmic face of the endoplasmic reticulum, their active center lies out/on the bilayer border.