Abstract
Summary
The activity of the enzyme system which produces taurine from PAPS and serine in chick liver has been tested for regulation by intermediates of the transsulfuration pathway. The l-isomer of methionine, SAM, homocysteine, cysteine, and CSA produced significant decreases in the activity of this enzyme system. Low concentrations of d-methionine, and isethionate, a product of taurine deamination, gave a slight enhancement of enzyme activity. Cysteic acid, a postulated enzyme-bound intermediate of this enzyme system, produced increased activity at low enzyme-protein concentration but no effect at higher concentrations. These data suggest the existence of a switchover mechanism in the biosynthesis of taurine in the animal from these two sulfur sources.
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