嗜麦芽窄食单胞菌DHHJ角蛋白酶的理化性质

Physical and Chemical Properties of Keratinase from Stenotrophomonas maltophilia DHHJ

通过羽毛粉的酶解实验，研究了嗜麦芽窄食单胞菌（Stenotrophomonas maltophilia）DHHJ突变菌株的粗酶液的理化性质。结果表明，酶水解羽毛的最适条件为pH7．8、温度50℃，在pH7．0～8．0、60℃以下酶活较稳定。Ca^2＋、Ba^2＋、Cu^2＋、Na^＋、K^＋和Mg^2＋对粗酶活力有促进作用，而Hg^2＋、Cd^2＋、Pb^2＋、Zn^2＋和苯甲基磺酰氟（PMSF）则对粗酶活力有抑制作用。对粗酶液进行了十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS—PAGE），根据测定结果认为该角蛋白酶可能为复合酶，由两个亚基构成，分子量分别为141kD和119kD，并认为这是一种新型角蛋白酶。

Physical and chemical properties of crude enzyme extracted from mutant strain of Stenotrophomonas maltophilia DHHJ was studied. It was confirmed that optimal conditions for feather - degradation by the crude enzyme from the strain were pH 7.8 and temperature 50 ℃, respectively. The enzyme was stable at pH between 7.0 - 8.0 and at temperature up to 60 ℃. The activities of the crude enzyme were enhanced by Ca^2＋ , Ba^2＋, Cu^2＋, Na^＋ , K ^＋ and Mg^2＋ and inhibited by Hg^2＋ , Cd^2＋ , Pb^2＋ , Zn^2＋ as well as Phenylmethanesulfonyl fluoride （PMSF）. Because of being inhibited by PMSF, keratinase produced by Stenotrophomonas maltophilia DHHJ may belong to serine - protease type. In addition, data obtained from sodium dodecyl slfate -polyacrylamide gel electrophoresis （SDS -PAGE） indicated that the crude enzyme is composed of two subunits and their molecular mass were 141 kD and 119 kD, respectively. The enzyme may be regarded as a new kind of keratinase.