Participation of adenylate kinase in the regulation of chloroplast energy exchange

Autor: I. M. Kartashov
Rok vydání: 2009
Předmět:
Zdroj: Biophysics. 54:593-597
ISSN: 1555-6654
0006-3509
DOI: 10.1134/s0006350909050078
Popis: The influence of adenylate kinase on the rates of glucose-6-phosphate synthesis and ferricyanide reduction in a system containing chloroplasts, hexokinase, and ADP at low concentration during photophos-phorylation has been studied. It has been found that the addition of adenylate kinase into the reaction medium under phosphorylation results in a simultaneous increase in the rate of ferricyanide reduction and glucose-6-phosphate synthesis. In this case, the ratio of glucose-6-phosphate formed to the quantity of ferricyanide reduced was close to unity as the concentration of adenylate kinase in the medium increased. The concentrations of glucose-6-phosphate and ferricyanide reduced in the system sharply increased with time; at the same time, no significant decrease in ADP concentration and AMP accumulation by the methods available was found. Hence, the limiting factors in these reactions are not the concentrations but the rates of diffusion of the substrates. Presumably, diffusion limitations in the system are eliminated owing to the participation of adenylate kinase. The results obtained are discussed in terms of the model according to which the regulation of the diffusion of adenine nucleotides and the control of regeneration of ATP according to its requirements in correlation with other regulation mechanisms can occur in chloroplasts upon adenylate kinase functioning by direct and reverse connection of the shuttle type.
Databáze: OpenAIRE
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