| Abstract: | Using affinity chromatography on diasorb-L-arginine and polyacrylamide gel electrophoresis, soluble carboxypeptidase H (E. C. 3.4.17.10) has been isolated from cat brain cortex and purified 598-fold with a 16% yield. The enzyme has a molecular mass of 50 kDa, consists of one polypeptide chain, and displays the maximum activity at pH 5.6. Carboxypeptidase H is a thiol-dependent metalloenzyme and contains a Zn2+ ion in its active center. The Km and V values for dansyl-Phe-Leu-Arg are 100 +/- 5 microM and 12.5 +/- 1.4 microM/min/mg of protein, respectively. The existence of two forms of soluble carboxypeptidase differing in isoelectric points and pH optima has been demonstrated. The enzyme with a pI of 4.8 has a pH optimum at 5.5-5.6, while that with a pI of 5.25-at 6.0. |
