A procedure for the purification of an ornithine carbamoylphosphate transferase isolated from a Staphylococcus aureus strain is reported. The procedure consists of the following steps: water extraction of the crude enzyme by autolysis under a toluene layer of the acetone dried bacteria cells, lyophilization of the crude extract, molecular sieving chromatography on a Bio Gel P‐150 column and as a final step the electrophoresis on Sephadex G‐200 plates.A 100‐fold purification with a 50% yield is realized. The purified preparation so obtained appeared to be pure on the basis of acrylamide gel electrophoresis, thin layer chromatography, immunodiffusion and immunoelectrophoresis.The apparent molecular weight of the enzyme as determined by molecular sieve chromatography is 200 000 ± 30 000.The Km value for l‐ornithine as substrate is 3 mM and for carbamoylphosphate 0.7 mM. Arrhenius activation energy is 13 775 cal/mol. NH2‐terminal amino acid is glycine: COOH‐terminal amino acid is glutamic acid.Two unmasked SH‐groups and two S‐S interchain bridges per molecule were found.
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