Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/227266

Title

Adenosine kinase from human erythrocytes: determination of the conditions required for assay in crude hemolysates

Author(s)

Kyd, Jennelle M.;  Bagnara, Aldo S.

Abstract

An assay suitable for initial velocity studies was developed to measure adenosine kinase (ATP: adenosine 5'-phosphotransferase, EC 2.7.1.20) activity in crude lysates of human erythrocytes. The pH optimum for the reaction was dependent on the ratio of Mg2+/ATP used in the assay. With a Mg2+/ATP ratio of 5.0, the pH optimum was 5.1 and only 10% of the maximal activity was retained at pH 7.3. When a Mg2+/ATP ratio of 0.50 was used, the pH optimum was 6.2, but 70% of the maximal activity was retained at pH 7.3. For assays performed at pH 7.3, the optimal Mg2+/ATP ratio was 0.50 for ATP concentrations between 0.50 and 2.0 mmol/l. Mg2+ was required for reaction, presumably to form the physiological substrate MgATP2-. However, excess free (uncomplexed) Mg2+ was a strong inhibitor of the enzyme at pH 7.3. At pH 7.3, the K(m) values for adenosine and MgATP2- were 0.66 μmol/l and 82 μmol/l respectively.

Publication type

Journal article

Source

Clinica Chimica Acta, Vol. 103, no. 2 (Apr 1980), pp. 145-153

Publication year

1980

FOR Code(s)

1103 Clinical Sciences

Keyword(s)

Adenosine kinase;  Adenosine triphosphate;  Blood and hemopoietic system;  Coformycin;  Divalent cations;  Erythrocytes;  Haemolysis;  Hydrogen-ion concentration;  Kinetics;  Magnesium;  Phosphotransferases;  Thin layer chromatography

Publisher

Elsevier

ISSN

0009-8981

Publisher URL

http://dx.doi.org/10.1016/0009-8981(80)90206-5

Copyright

Copyright © 1980. Published by Elsevier B.V.

Peer reviewed