Evidence of inactivation of pineal indoleamine N-acetyltransferase by protein thiol:disulfide exchange.
Pineal indoleamine N-acetyltransferase activity in homogenates is rapidly reduced at pH 6.8 by treatment with cystamine or arginine vasotocin. Other disulfides including glutathione disulfide, penicillamine disulfide, and N,N'-diacetylcystamine are either ineffective or less effective. The diamine analogous to cystamine, diaminohexane, is also ineffective. Inactivation by cystamine is accelerated at higher pH and is temperature- and time-dependent. It was also found that cystamine treatment inactivated N-acetyltransferase in intact pineal cells. Treatment with dithiothreitol reactivated the cystamine- or arginine vasotocin-inactivated enzyme formed in broken cell preparations and the cystamine-inactivated enzyme formed in intact cells. These observations indicate that pineal N-acetyltransferase can be inactivated by protein thiol:disulfide exchange; further research is required to ascertain whether this mechanism is of physiological significance.
D000123:Acetyltransferases / Q000378:metabolism*; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003538:Cystamine / Q000494:pharmacology; D004220:Disulfides / Q000494:pharmacology*; D004229:Dithiothreitol / Q000494:pharmacology; D004793:Enzyme Reactivators; D004794:Enzyme Repression; D008297:Male; D010870:Pineal Gland / Q000201:enzymology*; D051381:Rats; D013696:Temperature; D014668:Vasotocin / Q000494:pharmacology
D004220:Disulfides; D004793:Enzyme Reactivators; D003513:Cycloheximide; D000123:Acetyltransferases; D001191:Arylamine N-Acetyltransferase; D003538:Cystamine; D004229:Dithiothreitol; D014668:Vasotocin