Microassay of human erythrocyte catechol-O-methyltransferase: Removal of inhibitory calcium ion with chelating resin

F. A. Raymond, R. M. Weinshilboum

Research output: Contribution to journalArticle

85 Scopus citations

Abstract

A radiochemical micromethod for the determination of catechol-O-methyltransferase (COMT) activity in human red blood cells (RBC) is described. The method avoids artifacts that occur with other assay procedures. Erythrocyte lysates are exposed to a particulate chelating agent (Chelex-100) to remove endogenous divalent cations that inhibit COMT. 3,4-Dihydroxybenzoic acid rather than norepinephrine is used as a substrate to increase both the sensitivity and the reproducibility of the procedure. An internal standard of purified rat liver COMT is added to lysates to detect possible variations in endogenous activators or inhibitors of the enzyme. Blood samples from 373 unselected subjects age 16-18 were assayed for RBC COMT activity with this assay procedure. The COMT activity in these blood samples ranged from 3-25 units with a mean activity of 11.3 ± 4.2 (mean ±S.D.).

Original languageEnglish (US)
Pages (from-to)185-194
Number of pages10
JournalClinica Chimica Acta
Volume58
Issue number2
DOIs
StatePublished - 1975

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Biochemistry, medical

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