title: [Effect of S-nucleosyl-L-homocysteines on the activity of DNA methylases].
abstract: It was studied effect of S-adenosyl, -uridyl, -citidyl and -inosyl homocysteines on activity of bacterial adenine and cytosine methylases from E. coli CK as well as on guanine methylase specific for DDVI phage. S-adenosyl homocysteine was shown to be the strong inhibitor of methylation; 10 micrometer of the substance inhibited all the enzymes studied by 98--99%. Use of total enzymatic preparations did not enable to find a difference in affinity of S-uridyl, -citidyl, and -inosyl homocysteines to various DNA methylases studied. All these preparations inhibited DNA methylases by 55--65%. Increase in concentration of inhibitor up to 20 micrometer did not elevate the inhibitory effect. Action of S-nucleosyl homocysteines did not depend on the type of acceptory DNA.
mesh_terms: D003090:Coliphages / Q000201:enzymology; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli / Q000201:enzymology; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008745:Methylation; D008780:Methyltransferases / Q000037:antagonists & inhibitors*
chemical_list: D006710:Homocysteine; D008780:Methyltransferases; D004248:DNA (Cytosine-5-)-Methyltransferases
vernacular_title: O vliianie S-nukleozil-L-gomotsisteinov na aktivnost' nekotorykh metilaz DNK.