分枝犁头霉α-半乳糖苷酶的氨基酸组成及化学修饰

α-半乳糖苷酶进行氨基酸组分分析,结果为含有较多的酸性及巯水性氨基酸,较少的组氨酸、酪氨酸及半胱氨酸。 用几种蛋白质侧链修饰试剂对α-半乳糖苷酶进行化学修饰。在一定条件下,当巯基及酪氨酸残基分别被NEM、IAA及NAI修饰后,酶活力不受影响,说明这些基团与活力无关。当羟基、组氨酸及色氨酸残基分别被EDC、DEP、NBS及HNBB修饰后,酶活力大幅度下降,说明这些基团或者参与了酯催化作用或者位于酯活性位区附近。

The Amino Acids Composition and Chemical Modifiocation of α-galactosidase From Absidia Ramosa

The amino acid analysis of purified a-galactosidase showed that the enzyme was rich in acidic as well as hydrophobic amino acids but poor in cysteine, histidine and tyrosine.The effects of some protein modification reagents on the a-galactosidase activity have been studied.The enzyme was not effected by NEM, IAA or NAI modification suggesting that thiol group or tyrosine residues were non-essential for enzyme activity. But the enzyme activity was remarkably decreased after EDC, DEP, NBS or HNBB modification. This results indicated that carboxyl groups, tryptophan and histidine residues seemed to be essential for the catalytic activity or located at the active site of the a-galactosidase.