Mathematical modeling of kinetics of adenosine-5’-triphosphate hydrolysis catalyzed by the Zn2+ ion in the pH range 8.5–9.0

Autor: E. Z. Utyanskaya, M. G. Neigauz, A. E. Shilov, B. V. Lidskii
Rok vydání: 2000
Předmět:
Zdroj: Kinetics and Catalysis. 41:462-484
ISSN: 1608-3210
0023-1584
DOI: 10.1007/bf02756063
Popis: The kinetics of adenosine-5’-triphosphate (ATP) hydrolysis catalyzed by Zn2+ at pH 8.5–9.0 is analyzed by numerical simulation. The rates of product formation (adenosine diphosphate (ADP) and adenosine monophosphate (AMP)) are determined by a conformational transformation. In the sequence of steps of mutual transformations of cyclic (Cy) pH-dependent species, which are active in ATP hydrolysis to ADP, and open (Op) species, the rate-limiting step is the slow isomerization of ZnATP2-complexes. This slow step is determined by the abstraction of the OH- group from a pentacovalent intermediate catalyzed by H3O+. In the Op species,Zn 2+ is bound to the phosphate chain. In the Cy species, which can be hydrolized to ADP, Zn2+ coordinates a nitrogen atom in position 7 and γ-phosphate. The mutual transformations of conformers occur via pentacovalent intermediates with the participation of γ-phosphorus and include pseudotransformations. In the direct transformation CyOH-⦚r OpOH-, pseudotransformation is a rate-controlling step. The deprotonated open monomeric form OpOH- is inactive in hydrolysis. Within the framework of the dimeric model and a more complex model that accounts for the role of trimeric associates ZnATP2-, the general scheme of intermediate transformations is considered that accounts for the existence of a pH-independent pathway of hydrolysis. The rate and equilibrium constants are estimated. Concentration profiles for intermediate products during hydrolysis are described.
Databáze: OpenAIRE
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