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Glycine N-methyltransferase and regulation of S-adenosylmethionine levels.

ABSTRACT: Methylation is a major biological process. It has been shown to be important in formation of compounds such as phosphatidylcholine, creatine, and many others and also participates in epigenetic effects through methylation of histones and DNA. The donor of methyl groups for almost all cellular methylation reactions is S-adenosylmethionine. It seems that the level of S-adenosylmethionine must be regulated in response to developmental stages and metabolic changes, and the enzyme glycine N-methyltransferase has been shown to play a major role in such regulation in mammals. This minireview will focus on the latest discoveries in the elucidation of the mechanism of that regulation.

SUBMITTER: Luka Z

PROVIDER: S-EPMC2755656 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature

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Glycine N-methyltransferase and regulation of S-adenosylmethionine levels.

Luka Zigmund Z Mudd S Harvey SH Wagner Conrad C

The Journal of biological chemistry 20090529 34

Methylation is a major biological process. It has been shown to be important in formation of compounds such as phosphatidylcholine, creatine, and many others and also participates in epigenetic effects through methylation of histones and DNA. The donor of methyl groups for almost all cellular methylation reactions is S-adenosylmethionine. It seems that the level of S-adenosylmethionine must be regulated in response to developmental stages and metabolic changes, and the enzyme glycine N-methyltra ...[more]

PMID: 19483083

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A disulfide-bond cascade mechanism for arsenic(III) S-adenosylmethionine methyltransferase.

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| S-EPMC4356363 | biostudies-literature

High-throughput screening-compatible assays of As(III) S-adenosylmethionine methyltransferase activity.

Project description:Arsenic is a naturally existing toxin and carcinogen. As(III) S-adenosylmethionine methyltransferases (AS3MT in mammals and ArsM in microbes) methylate As(III) three times in consecutive steps and play a central role in arsenic metabolism from bacteria to humans. Current assays for arsenic methylation are slow, laborious, and expensive. Here we report the development of two in vitro assays for AS3MT activity that are rapid, sensitive, convenient, and relatively inexpensive and can be adapted for high-throughput assays. The first assay measures As(III) binding by the quenching of the protein fluorescence of a single-tryptophan derivative of an AS3MT ortholog. The second assay utilizes time-resolved fluorescence resonance energy transfer to directly measure the conversion of the AS3MT substrate, S-adenosylmethionine, to S-adenosylhomocysteine catalyzed by AS3MT. These two assays are complementary, one measuring substrate binding and the other catalysis, making them useful tools for functional studies and future development of drugs to prevent arsenic-related diseases.

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