Angiotensin Converting-like Enzyme From Catfish Gills: Purification And Characterization

Angiotensin converting-like enzyme was purified from catfish gills and investigated their main biochemical and kinetic characteristics. In order to provide the basis for catfish gills high value utilization and the study results as follows:1、The early stage of the experiment was extracted protease from three kinds of fish gills including grass carp, carp and catfish and determination of enzyme activity. Selected out catfish gills may contain this kind of angiotensin converting-like enzyme which can degrade ACE substrate HHL.2 、 Angiotensin converting-like enzyme was purified from catfish gills by ammonium sulfate precipitation, column chromatographies of DEAE-Toyopearl 650 M and Cellufine GCL-2000. After the final purification step, the enzyme was purified 46-fold, with a recovery of 2.8 % and a specific activity of 11.5 U/mg.3、The enzymatic properties were studied by RP-HPLC and the result shows that: the enzyme was stable between 20-40 ℃and extremely stable in the p H range 8.0-11.0. The optimal temperature and p H for the enzyme activity was 40 ℃ and 9.0, respectively. Further studies showed that the enzyme activity was rapidly decreased by K+ and Cu2+(1.0 mmol/L). The activity was inhibited by captopril(1.0 mmol/L). Using hippuryl-L-His-Leu as substrate, under the p H 9.0, 40 ℃, Km value was 0.18 mmol/L and Vmax was 1.57 mmol/min.