Abstract
The pathway of salicylate conversion to salicylurate has been demonstrated for the first time in vitro. A crude preparation of protein from beef liver "mitochondria" catalyzes the following reaction sequence: Salicylate + ATP + CoA [unknown] salicyl-CoA + PPi (1) Salicyl-CoA + glycine → salicylurate + CoA (2) In the over-all pathway, salicylurate formation was dependent on the presence of ATP, MgCl2, coenzyme A, glycine, and active enzyme. The crude enzyme catalyzed the conversion of salicylate to a compound identified as salicyl-CoA in a reaction dependent on ATP, MgCl2, and CoA. Salicylurate was also produced enzymatically from glycine and either chemically or enzymatically synthesized salicyl-CoA. The thioester linkages of both chemically and enzymatically synthesized salicyl-CoA were quite stable to alkaline hydrolysis, with half-lives averaging 44 min in 0.25 N KOH at 38°. The first or activating step was rate-limiting in salicylurate biosynthesis from salicylate when both activating and acylating reactions were assayed under approximately optimal conditions. Acyl-CoA:glycine N-acyltransferase activity (EC 2.3.1.13) was purified from the crude "mitochondrial" preparation into four protein fractions, each of which could utilize both salicyl-CoA and benzoyl-CoA as substrates.
ACKNOWLEDGMENT The authors wish to thank Dr. Sung Ling Yuan for his valuable technical assistance.
- Copyright © 1971 by Academic Press, Inc.
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