Biomedical subjects

N S Panteleeva

Publications and source records attributed to N S Panteleeva.

6 recordsLinked to original sources

PubMed1977

18O-exchange catalyzed by myosin, heavy meromyosin, heavy meromyosin subfragment 1 and their complexes with actin.

Myosin, HMM and HMM S1 catalyze 18O-exchange between P1 and H218O of the medium at an intermediate stage of ATP hydrolysis ("intermediate 18O-exchange") in the presence of Mg2+. Natural complexes of actomyosin and acto-HMM S1 do not catalyze intermediate 18O-exchange but facilitate "direct" or "medium" 18O-exchange (KH2P18O4 in equilibrium H2O) even without ATP. Reconstituted complexes of actomyosin, acto-HMM, acto-HMM S1, PABC-HMM S1, congo-myosin and TNP-myosin do not catalyze direct 18O-exchange in the presence of Mg2+ and absence of ATP. From the data obtained a hypothetical sequence of phosphorylation and 18O-exchange reactions in myofibril action has been suggested.

Actins↗

PubMed1977

[Oxygen isotope exchange reactions in synaptosomal plasmatic membrane system].

Mg2+-Dependent, Ca2+-activated adenosine triphosphatase (E. C. 3.6.1.4) of synaptosomal plasmatic membrane from cow brain catalyses isotopic exchange of oxygen atoms: KH2P18O 4 in equilibrium H2O, the degree of exchange depending on Ca2+ concentration. The 18O-exchange catalysis suggests that the enzyme under consideration acts as a transport ATPase.

Adenosine Triphosphatases↗

PubMed1977

[18 O-exchange during ATP and n-nitrophenylphosphate hydrolysis by Na, K-ATPase from bovine brain].

The reaction of the oxygen isotope exchange (18O-exchange) was studied in the course of the Na, K-ATPase reaction. It was shown that the intermediary and direct 18O-exchanges occurred in the system in the presence of both ATP and p-NPP. These findings are indicative of the same intermediate during the hydrolytic process in both cases. The intermediary 18O-exchange was activated by N-ethylmaleimide, hydroxylamine and 2.0--1.5 18O atoms, respectively. The detection of 18O-exchange Ouabain had no effect on the exchange. The levels of intermediary 18O-exchange during ATP and p-NPP hydrolyses were equal to 1.3--1.4 and 2.0--1.5 18O atoms, respectively. The detection of 18O-exchange reactions at the intermediary steps of both ATP and p-NPP hydrolyses implies the identity of certain stages in the destruction of these substrates by Na, K-ATPase.

Adenosine Triphosphatases↗

PubMed1977

[18 O-exchange reactions catalyzed by myosin of calf intestine smooth muscle].

18O-exchange reactions of smooth muscle myosin of calf intestine were studied. Smooth muscle myosin, similar to skeletal myosin, catalyses two types of 18O-exchange reactions--intermediate and direct. Only quantitative differences of the exchange intensity are observed. 18O-exchange dependence on bivalent cation and nucleotide nature is found. The comparison of 18O-exchange characteristics for myosins of smooth and skeletal muscles confirms the hypothesis on the similarity of molecular mechanisms of ATP hydrolysis by myosin from different muscle types.

Adenosine Triphosphate↗

PubMed1976

[18 O-exchange reactions catalyzed by subfragment 1 of myosin molecule].

18 O-exchange properties of enzymically active proteolytic fragment of myosin molecule--subfragment 1 were studied. It was shown that 18O-exchange activity of subfragment 1 is similar to that of parental myosin and its other proteolytic fragment--heavy meromyosin. The experimental data suggest that the 18O-exchange activity is an integral property of myosin and is not determined by its contaminations.

Myosins↗

PubMedDate not supplied

[Modern views on mechanism of ATP hydrolysis by myosin (on the 40th anniversary of myosin enzymatic activity discovery)].

Literature data and the author's materials concerning the intermediate stages of ATP hydrolysis by myosin and actomyosin are reviewed. The scheme of hydrolytic stages based on the application of fluorescent and UV spectroscopic stop-flow and 18O exchange methods is discussed. Some unsolved problems of the hydrolytic mechanism and its relation to energy transduction in the mechanochemical act are also considered.

Actomyosin↗