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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
