Study on a new aminopeptidase from hen's egg

An aminopeptidase Ey is a newly discovered enzyme of hen's egg yolk. about 95% of the totalactivity was found in the yolk plasma fraction,with the most remainder in the yolk granule fraction。The highly purified fraction from plasma showed about 13,000-folds higher spcific activities thanyolk plasma. Polyacrylamide gel electrophoresis revealed that the enzyme was homogeneous.The bound enzyme in The granule was extracted with 3% NaCl and was partially purified. The solubleand bound forms of aminopeptidase differ in solubility, molecular weight, heat stability，optimal pH and Km. The molecular weight determination with gel filtration on Toyo-pearl HWsindicated that the values of the aminopeptidase Eyp from plasma and Eyg from granule were 360,000and 700000,respectively. The Km value for L-MCA at ph6.5 of The aminopeptidase Eyp from plasma fraction wasdetermined to be 0.01 ml，while the km value of Eyg from granule fraction was 0.8 mM at ph7.5 . the aminopeptidase Eyp wasstable between 30 and 50 C for 10min at ph7.5 and 30 Cwhile the aminopeptidase Eyg was activated with increasing temperature from 30 to 60 C. the metalrequirement suggests that the soluble aminopeptidase from plasma, Eyp，is similar to aminopeptidase Co from the yeast Saccharomyces cerevisiae。

An aminopeptidase Ey is a newly discovered enzyme of hen's egg yolk. about 95 % of the total activity was found in the yolk plasma fraction,with the most remainder in the yolk granule fraction. The highly purified fraction from plasma showed about 13,000-folds higher spcific activities than that of yolk plasma. Polyacrylamide gel electrophoresis revealed that the enzyme was homogeneous. The bound enzyme in the granule was extracted with 3 % NaCl and was partially purified. The soluble and bound forms of aminopeptidase differ in solubility, molecular weight, heat stability, optimal pH and Km. The molecular weight determination with gel filtration on Toyo-pearl HWs indicated that the values of the aminopeptidase Eyp from plasma and Eyg from granule were 360,000 and 700,000, respectively. The Km value for L-MCA at pH 6.5 of the aminopeptidase Eyp from plasma fraction was determined to be 0.01 ml, while the km value of Eyg from granule fraction was 0.8 mM at pH 7.5. The aminopeptidase Eyp was stable between 30 and 50 ゜C for 10 min at pH 7.5 and 30゜C, while the aminopeptidase Eyg was activated with increasing temperature from 30 to 60 ゜C. The metal requirement suggests that the soluble aminopeptidase from plasma, Eyp, is similar to aminopeptidase Co from the yeast Saccharomyces cerevisiae.