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. 1995 Jul;48(7):641–644. doi: 10.1136/jcp.48.7.641

Thiol methyltransferase activity in colonocytes and erythrocyte membranes.

W J Babidge 1, S H Millard 1, W E Roediger 1
PMCID: PMC502715  PMID: 7560171

Abstract

AIMS--To verify the improved thiol methyltransferase (TMT) assay and measure activity in isolated colonocytes and erythrocyte membranes of the same subjects. METHODS--High performance liquid chromatography with radioactivity detection was used to measure 14C-methylmercaptoethanol formation, the reaction product of cell extracts incubated with mercaptoethanol and 14C-S-adenosylmethionine. RESULTS--Verification of radiolabelled 14C-methylmercaptoethanol was by exogenous addition of methylmercaptoethanol and simultaneous ultraviolet detection at 214 nm. Using a substrate concentration of 10 mM mercaptoethanol, the Km for S-adenosylmethionine was 25 microM. The sensitivity of the radioactive method was 2 pmol, with coefficients of variation of 7% within assay and 6.4% between assay. TMT activities (mean +/- SE; n = 17) were 471 +/- 64 pmol/hour/mg protein for colonocytes and 73 +/- 7 pmol/hour/mg protein for erythrocyte membranes. CONCLUSIONS--The direct assay of TMT activity is sensitive, specific and eliminates concern over non-enzymatic methylation of thiol compounds. High activities in colonic epithelial cells deserve evaluation in disease states.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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