title: Photoaffinity labeling of catechol O-methyltransferase with 8-azido-S-adenosylmethionine.
abstract: An in vitro system using an enzyme extract containing ATP:L-methionine S-adenosyltransferase from Escherichia coli MRE 600 cells was used to synthesize 8-azido-S-adenosyl-L-methionine from methionine and 8-azidoadenosine 5'-triphosphate. In the absence of ultraviolet light and analog can serve as a methyl donor for porcine catechol O-methyltransferase. Photolysis of 8-azido-S-adenosyl[35S]methionine in the presence of catechol O-methyltransferase results in covalent incorporation. Addition of either authentic S-adenosylmethionine or S-adenosylhomocysteine, but not adenosine 5'-monophosphate, to the photolysis reaction mixture eliminates the photoincorporation. These results indicate that the incorporation is occurring at the S-adenosylmethionine binding site in the catechol O-methyltransferase.
mesh_terms: D000345:Affinity Labels / Q000494:pharmacology*; D000818:Animals; D001386:Azides / Q000138:chemical synthesis / Q000494:pharmacology*; D002394:Catechol O-Methyltransferase / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008716:Methionine Adenosyltransferase / Q000378:metabolism; D010782:Photolysis; D012436:S-Adenosylmethionine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D013056:Spectrophotometry, Ultraviolet; D013552:Swine
chemical_list: D000345:Affinity Labels; D001386:Azides; D012436:S-Adenosylmethionine; C037207:8-azido-S-adenosylmethionine; D002394:Catechol O-Methyltransferase; D008716:Methionine Adenosyltransferase