PINEAL SEROTONIN N-ACETYLTRANSFERASE ACTIVITY: PROTECTION OF STIMULATED ACTIVITY BY ACETYL-CoA AND RELATED COMPOUNDS |
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| Authors: | Sue Binkley D C Klein Joan L Weller |
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| Institution: | Section on Physiological Controls, Laboratory of Biomedical Sciences, National Institute of Child Health and Human Development, National Institutes of Health, Building 6, Room 130, Bethesda, MD 20014, U.S.A. |
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| Abstract: | —Rat pineal serotonin N—acetyltransferase activity increases 30–70-fold at night in the dark and then decreases rapidly when animals are exposed to light. Activity of the enzyme is also stimulated by l -norepinephrine in organ culture. When homogenates of glands stimulated by dark in vivo or NE in vitro are incubated at 37°C, enzyme activity will also rapidly decrease. This decrease can be prevented by one of the cosubstrates of the enzyme, acetyl–CoA. Protection can also be conferred by cysteamine (β-mercaptoethylamine, HS–CH2–CH2–NH2) which is the terminal portion of the CoA molecule. This protection mechanism could be involved in the physiological control of enzyme activity. |
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