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S-methylation of captopril. Demonstration of captopril thiol methyltransferase activity in human erythrocytes and enzyme distribution in rat tissues.

Authors :
Drummer OH
Miach P
Jarrott B
Source :
Biochemical pharmacology [Biochem Pharmacol] 1983 May 15; Vol. 32 (10), pp. 1557-62.
Publication Year :
1983

Abstract

The presence of a methyltransferase enzyme in human red blood cells (RBCs) capable of S-methylation of captopril is described. The apparent Michaelis-Menten (Km) constant for captopril was 0.5 mM and the maximum velocity (Vmax) was 0.391 pmoles S-methylcaptopril (mg protein)-1 min-1. There is some evidence presented to show that S-methylcaptopril inhibited its own formation with a ki value of 5.81 mM. Captopril thiol methyltransferase activity was also examined in rat tissues and was found to be present in all tissue studied. Subcellular localisation studies in rat liver suggest that the enzyme was microsomal in origin. The order of activity was liver greater than heart greater than spleen greater than lung greater than kidney much greater than RBC (rat). This tissue distribution was quite different from previous studies using other thiol substrates and is consistent with more than one form of thiol methyltransferase enzyme in tissues.

Details

Language :
English
ISSN :
0006-2952
Volume :
32
Issue :
10
Database :
MEDLINE
Journal :
Biochemical pharmacology
Publication Type :
Academic Journal
Accession number :
6344869
Full Text :
https://doi.org/10.1016/0006-2952(83)90327-1