Abstract
The regulation of phenylethanolamine N-methyltransferase degradation in vivo is mediated via adrenal glucocorticoids. The glucocorticoid inhibition of PNMT degradation is mediated via an endogenous adrenal stabilizing factor whose levels are controlled by glucocorticoids. A partially purified preparation of the endogenous stabilizing factor has an absorption maximum of 265 nm and migrates with S-adenosylmethionine and 3',5'-cyclic AMP on paper chromatography. S-adenosylmethionine is highly effective in stabilizing PNMT against both thermal and tryptic degradation, while cyclic AMP is ineffective as a stabilizing agent. S-adenosylhomocysteine, the demethylated product formed from S-adenosylmethionine during transmethylation stabilizes PNMT against tryptic but not thermal degradation. S-adenosylmethionine administration to hypophy-sectomized rats partially restores PNMT levels in vivo and enzyme thermal stability in vitro.
ACKNOWLEDGMENTS The authors wish to express their gratitude to Dr. Helena Kramer of the Department of Psychiatry and Behavioral Sciences for her invaluable help in the statistical analysis of the regression data.
- Copyright © 1979 by Academic Press, Inc.
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