PubMed Health⌕ Search

Biomedical subjects

V B Evstigneev

Publications and source records attributed to V B Evstigneev.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

[Relationship between the electron structure of phosphates and the problem of ATP synthesis and utilization].

The nature of macroergic bonds and some problems of ATP formation and utilization are considered in terms of electron structure of phosphates. The main acting compound in the ATP synthesis and in the reactions of transfer and utilization of the energy of macroergic bonds as well, is ATP terminal phosphate or phosphoryl group which in the free state is a monomeric methaphosphate-ion. High reactive ability of monomeric methaphosphate-ion, its affinity of lown electrom pairs is conditioned by the presence of a vacant sp3-orbitals in phosphor atom of methaphosphate-ion. Therefore in the reactions with ATP participation the phosphoryl group plays the role of electrophilic agent. Formation of intermediate methaphosphate-ion preceding the synthesis of ATP from ADP during substrate phosphorylation results from the breakage of O--P bond, during which both electrons which form the bond stay in the oxygen atom. Another possible pathway of methaphosphate-ion formation is the ejaction of the electron from ortophosphate dianion with the help of suitable acceptor of the electrons, by light-stimulated pigment system of chloroplasts or chromatophores or singlet oxygen liberated during the decomposition of hydrogen peroxide with catalase. Due to the redistribution of electron density in the phosphate radical the latter turns into the monomeric methaphosphate-ion bound to ADP with the formation of ATP.

Adenosine Triphosphate↗
PubMedDate not supplied

[Role of singlet-excited and triplet states in chlorophyll photooxidation].

Effect of p-benzoquinone concentration [Q] on the yield of ion-radicals during photooxidation of chlorophyll a with p-benzoquinone was studied by the method of impulse photoconductivity. It has been shown that in the studied range [Q] = 10(-6)--10(-1) M the relationship delta n ([Q]) has a bell-like shape with the maximum at [Q] approximately 10(-3) M. From the relationship obtained the ratio beta = delta ns/delta nt of the contributions of singlet--excited (Chl) and triplet (Chl) states of the pigment into the total yield of ion-radicals is evaluated: for [Q] less than or equal to 10(-1) M beta less than or approximately 10(-3). Primary contribution of the triplet state to the formation of ion-radical is explained, first, by a larger, as compared to the singlet-excited state, life time of the state Chl in solution and second, by the fact that the ion-radical pair 3(Chl+Q-) in the triplet state regenerates less effectively to Chl+Q, than the pair (Chl+Q-).

Benzene Derivatives↗