北京鸭脑钙调素的分离纯化和性质的研究

钙调素(Calmodulin,简称CaM)是一种多生理功能的调节蛋白,在脑的功能活动中有重要作用。本文采用苯基琼脂糖(phenyl-Sepharose CL 4B)层析和葡聚糖凝胶(Sephadex G-50)过滤法,从北京鸭脑中分离纯化出CaM。纯化的CaM经SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)和等电聚焦(IEF)电泳鉴定均为一条区带。分子量为19kD,等电点(pI)为4.15,消光系数为1.83。 对纯化的鸭脑CaM的活性和性质进行了研究。它可明显地激活牛环核苷酸磷酸二酯酶活性,在有Ca~(2+)存在的条件下,SDS-PAGE中出现电泳迁移速度的改变,紫外吸收光谱具有已知CaM特有的吸收多峰形,并观察了Ca~(2+)对荧光发射光谱的影响。其氨基酸组成中,1/3是酸性氨基酸,苯丙氨酸和酪氨酸的比例为8:2。与猪CaM和牛CaM的物理化学性质作了比较。

Purification And Characterization of Calmodulin From Peking Duck Brain

Calmodulin (CaM) was separated from Peking duck brain extract by Phenyl-Sepharose affinity ohromatography and further purified by Sephadex G-50. The purified CaM was shown to be homogeneous by SDS-PAGE and IEF with a molecular weight of 19,000, pI of 4.15, and an extinction coefficient ε2761m 1% of 1.83. The characteristic mobility change of CaM in the presence of Ca2+ was observed.The Ca2+-activition of bovine cyclic nucleotide phosphodiesterase could be enhanced by the addition of CaM. Among 146 amino acid residues, there are 23 aspartic acid, 25 glutamic acid, and no cysteine and tryptophan, the phenylala-nine/tyrosine ratio is high (8:2). Its UV absorption peaks occur at about 252,259, 265, 268.5 and 276nm. The enhancement of fluorescence of CaM could be induced by Ca2+. Some of physical properties of porcine, bovine and duck CaM are compared.