[Daily variations in S-adenosylmethionine content and oxyindole-O-methyltransferase activity in rat epiphysis].
Rat epiphysis was found to contain a relatively high amount of S-adenosylmethionine (SAM), which undergoes daily variations with a maximum in the middle of the daytime period and a minimum at the night-time phase. The variations are of endogenous type and are persistent in blinded animals. On the contrast, upon continuous illumination the SAM level in rat epiphysis is decreased and impaired. The activity of oxyindole-O-methyltransferase, the terminal enzyme of epiphysial melatonin biosynthesis which consumes methyl groups of SAM, is not subjected to daily variations. It is demonstrated that the artefact of the previously observed daily variations in the oxyindole-O-methyltransferase activity is due to day-to-night changes in SAM content.
D000121:Acetylserotonin O-Methyltransferase / Q000378:metabolism*; D000818:Animals; D001766:Blindness / Q000378:metabolism; D002940:Circadian Rhythm; D004838:Epiphyses / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D008297:Male; D008780:Methyltransferases / Q000378:metabolism*; D051381:Rats; D012436:S-Adenosylmethionine / Q000378:metabolism*
D012436:S-Adenosylmethionine; D008780:Methyltransferases; D000121:Acetylserotonin O-Methyltransferase
Sutochnyĭ ritm soderzhaniia S-adenozilmetionina i aktivnost' oksiindol-O-metiltransferazy v épifize krys.