BETA-ETHYLMALATE SYNTHETASE.

Rabin, Robert (Albert Einstein Medical Center, Philadelphia, Pa.), Henry C. Reeves, and Samuel J. Ajl. beta-Ethylmalate synthetase. J. Bacteriol. 86:937-944. 1963.-Pseudomonas aeruginosa, when grown in an inorganic salts medium with butyrate as the sole carbon source, produced an enzyme which catalyzed the condensation of butyryl coenzyme A (CoA) and glyoxylate to form beta-ethylmalic acid. Maximal activity was found in the 40 to 60% (NH(4))(2)SO(4) fraction of cell-free extracts. Mg(++) was stimulatory, and the optimal pH was 8.0 to 8.5. beta-Ethylmalic acid-C(14) was demonstrable in paper chromatograms when either glyoxylate-1-C(14) or butyryl CoA-3-C(14) was included in complete systems incubated anaerobically. When either glyoxylate, butyryl CoA, or enzyme was omitted, beta-ethylmalate was not detected. Further evidence that beta-ethylmalic acid-C(14) was the product of the condensation of butyryl CoA-3-C(14) and nonlabeled glyoxylate was provided by synthesis of the derivative 5-ethyluracil-C(14). The derivative was recrystallized to constant specific activity and identified by its melting point and spectral properties.