Jun 5, 1989

Kinetic properties and inhibition of human T lymphoblast deoxycytidine kinase

The Journal of Biological Chemistry
N S DattaI H Fox

Abstract

The kinetic properties of 50,000-fold purified cultured human T lymphoblast (MOLT-4) deoxycytidine kinase were examined. The reaction velocity had an absolute requirement for magnesium. Maximal activity was observed at pH 6.5-7.0 with Mg:ATP for 1:1. High concentrations of free Mg2+ or free ATP were inhibitory. Double reciprocal plots of initial velocity studies yielded intersecting lines for both deoxycytidine and MgATP2-. dCMP was a competitive inhibitor with respect to deoxycytidine and ATP. ADP was a competitive inhibitor with respect to ATP and a mixed inhibitor with respect to deoxycytidine. dCTP, an important end product, is a very potent inhibitor and was a competitive inhibitor with respect to deoxycytidine and a non-competitive inhibitor with respect to ATP. TTP reversed dCTP inhibition. The data suggest that (a) MgATP2- is the true substrate of deoxycytidine kinase; (b) the kinetic mechanism of deoxycytidine kinase is consistent with rapid equilibrium random Bi Bi; (c) deoxycytidine kinase may be regulated by its product ADP and its end product dCTP as well as the availability of deoxycytidine. While many different nucleotides potently inhibit deoxycytidine kinase, their low intracellular concentrations make their re...Continue Reading

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Mentioned in this Paper

Molting
T-Lymphocyte
2'-deoxycytidine 5'-triphosphate
Magnesium Measurement
Protoplasm
Deoxycytidine Monophosphate
DCK gene
Nucleotides
Metabolic Inhibition
2'-deoxycytidine 5'-triphosphate, magnesium salt

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