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- Title
Synthesis and Breakdown of Citric Acid with Crystalline Condensing Enzyme.
- Authors
STERN, JOSEPH R.; SHAPIRo, BENYAMIN; OCHOA, SEVERO
- Abstract
THE synthesis of citric acid from acetate, adenosine triphosphate and oxalacetate by soluble enzyme preparations from pigeon liver has been previously reported1. The system requires magnesium ions (Mg++) or manganese ions (Mn++) and coenzyme A as co-factors. Novelli and Lipmann2 reported synthesis of citrate in E. coli extracts with acetyl phosphate and oxalacetate as substrates. We find that, in this case, at least two enzymes are required (cf. also ref. 3). The first enzyme, (a), activates acetyl phosphate; the second, (b), catalyses the condensation of 'active' acetate and oxalacetate to citrate. The overall reaction is: acetyl phosphate + oxalacetate = citrate + orthophosphate. Enzyme (a) can be obtained from various bacteria (E. coli, Cl. butylicum, C. fœcalis) practically free from (b). The condensing enzyme (b), which is readily soluble, is present in a variety of animal tissues (heart, skeletal muscle, liver, kidney, brain), bacteria (E. coli, Azotobacter agilis, M. tuberculosis) and yeast4.
- Publication
Nature, 1950, Vol 166, Issue 4218, p403
- ISSN
0028-0836
- Publication type
Article
- DOI
10.1038/166403b0