Purification and Characterization of Ovoinhibitor from Japanese Quiail Egg White

Abstract

Ovoinhibitor was purified from Japanese quail egg whites to an electrophoretically homogeneous protein by alcohol fractionation, column chromatography on Sephadex G-75 and DEAE-Sepharose CL-6 B, isoelectrofocusing, and high-pressure liquid chromatography. Purified ovoinhibitor had a molecular weight of 53, 000 and a pI of 6.9. The carbohydrate content of the inhibitor was 1.6% by the phenol-sulfuric acid method. The inhibitor contained many aspartic acid residues and few methionine or phenylalanine residues. This ovoinhibitor inhibited bovine trypsin, bovine chymotrypsin, subtilisin, and porcine elastase. The inhibitor was stable in a wide pH range and was heat-resistant when the pH was acidic. Japanese quail ovoinhibitor resisted proteolysis by pepsin.