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

• Published in: Kinetics and catalysis Vol. 41; no. 4; pp. 462 - 484
• Main Authors: UTYANSKAYA, E. Z, LIDSKII, B. V, NEIGAUZ, M. G, SHILOV, A. E
• Format: Journal Article
• Language: Russian; English
• Published: Moscow Maik Nauka/Interperiodica 01.07.2000; Springer Nature B.V
• Subjects: Adenosine diphosphate; Adenosine monophosphate; Chemical equilibrium; Hydrolysis; Isomerization; Kinetics; Mathematical models; Transformations
• ISSN: 0023-1584; 1608-3210
• DOI: 10.1007/BF02756063

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,Zn2+ 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.