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1.
Photoreduction of NAD has been accomplished by a system consisting of the NAD-dependent hydrogenase from Alcaligenes eutrophus immobilized on CdS particles with formate as artificial electron donor. Enzymatically active NADH is formed under illumination of this system by visible light. Accumulation of the coenzyme dimer (NAD)2 was not detected. NAD photoreduction is supposed to proceed via the direct electron transfer from the semiconductor to the enzyme electron transport chain. However, NADH formation as a result of hydrogenase interaction with anion-radicals (CO2.-) formed in the course of formate photooxidation cannot at present be excluded. 相似文献
2.
V N Nikandrov N S Pyzhova V I Votiakov 《Biulleten' eksperimental'no? biologii i meditsiny》1987,104(7):49-51
The addition of ATP or 3,5-AMP (but not UTP, GTP, CTP, AMP, 2,3-AMP, ADP, inorganic pyrophosphate) at a final concentration of 10(-1) M into streptokinase solution, pH 7.0 or 9.5, causes a dramatic inhibition of streptokinase-induced fibrinolysis. The specificity of ATP effect is fully lost at pH 3.0, when all nucleotides completely inhibit the activating function of streptokinase. Ribose-5-phosphate causes a similar effect at pH 3.0. The character of nucleotide action on the activating function of streptokinase considerably differs from their influence on proteolytic reactions. 相似文献
3.
V N Nikandrov 《The International journal of biochemistry》1992,24(1):47-53
1. Several hypotheses have been advanced to explain the activating function of streptokinase. The predominant hypothesis suggests a stable equimolar streptokinase-plasmin(ogen) complex, activating free plasminogen by an active centre, which is located in the plasmin(ogen) part of the complex. 2. This hypothesis cannot explain a number of phenomena and certain accumulated experimental data, for example: rabbit and bovine plasminogen activation by streptokinase, not forming stable complexes with these plasminogens; possible activation with pH less than or equal to 2, in the presence of urea, during modification of streptokinase tyrosine residues, i.e. when these two proteins cannot form a stable complex. 3. On the basis of acquired experimental data the following concept is suggested: the activating function of streptokinase is oxygen-dependent and is realised with the help of superoxide radical due to the O(2-.)-generating ability of plasminogen and the O(2-.)-converting ability of streptokinase. 相似文献
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O A Kaziuchits V N Nikandrov G S Iankovskaia P G Rytik 《Biokhimii?a (Moscow, Russia)》1990,55(10):1847-1859
Photochemical oxidation with methylene blue as photosensitizer results in the destruction of one histidine residue in the streptokinase molecule. This process is characterized by the rate constant corresponding to the modification of free L-histidine and results in partial inactivation of the protein. The rate of protein photo oxidation and photoinactivation is pH-dependent. As can be judged from the results of CD spectroscopy and gel chromatography, in weakly acidic (but not in weakly alkaline) media the reaction results in conformation changes of the streptokinase globule which affect the state of the protein tryptophanyl residue. It was found that the imidazole group destroyed during the photooxidation reaction is not essential either for the specific activity of streptokinase or for the formation of is stable complex with human plasminogen. The specificity of modification of the streptokinase histidine residue during the photooxidation reaction is discussed. 相似文献
8.
Vitaly N. Nikandrov Oleg N. Murashko Galina V. Vorobyova Nelly S. Pyzhova Natalie V. Kvyatkovskaya Oksana A. Bartalevich 《International journal of peptide research and therapeutics》1997,4(4-6):497-502
Summary The formation of stable equimolar complexes of streptokinase or plasminogen with muscle lactate dehydrogenase or pyruvate
kinase, heart mitochondrial malate dehydrogenase and hepatic catalase at pH 7.4, 3.0 and 10.0 was first detected by differential
spectroscopy methods. All complexes, except those of plasminogen with dehydrogenases, were resistant to 6 M urea. Judging
from circular dichroism spectra, tertiary and secondary structures were considerably changed in the complexes. These changes
were significantly dependent upon the nature of interacting proteins; in some cases their structures were more ordered. NAD
(but not NADH) hampered the formation of streptokinase complexes with dehydrogenases. The plasminogen-activating function
of streptokinase and the ability of plasminogen to be activated by streptokinase in the complexes with oxidoreductases were
essentially unchanged. Pyruvate kinase induced a moderate (by 35%) increase in the streptokinase activating function. It is
assumed that the formation of complexes of streptokinase or plasminogen with enzymes may serve as a link in metabolic regulation
and/or intercellular interactions. 相似文献
9.
D. S. Pavlov V. V. Kostin I. V. Nechaev N. I. Shindavina V. Ya. Nikandrov 《Journal of Ichthyology》2009,49(11):1081-1091
The social status of hatchery-reared juveniles of Atlantic salmon Salmo salar at the age of 11–19 months in conditions of lack of shelters was investigated experimentally. It was demonstrated that biochemical
differentiation in such juveniles begins at the age of 13 months—one month before the first differences in the social status
of fish and four months prior to the beginning of smoltification. The dominants occupy bottom areas with shelters and extrude
the subordinates to the water column. The subordinates undergo smoltification or die from aggression of the dominants. Concentrations
of dopamine, noradrenalin, and of their metabolites in the brain of fish in the beginning of smoltification were higher in
the dominants and, by the end of smoltification, were higher in smolts. The social behavior of fish is considered to be one
of the ethological mechanisms of differentiation of salmon juveniles into smolts and parr. 相似文献
10.
The response time (simple mental reaction time) cooperation was estimated in 53 patients with focal lesions of the brainstem and diencephalon (thalamus). The cooperation between the left-and right-hand simple mental reactions to auditory and visual stimuli presented after a warning stimulus was analyzed to determine the morphological structures responsible for the cooperation of responses. The cooperation of the simple mental reaction remained normal in some of the subjects and was disturbed in others. In the latter case, the correlation coefficient between the left-and right-hand simple mental reactions to an auditory or visual stimulus or both stimuli simultaneously was changed. The disturbances were detected in patients with lesions of the tectum at the boundary between the medulla and the pons and in those with affected lateral regions of the thalamus. 相似文献