烟草叶片蔗糖酶的化学修饰

采用PMSF、NBS、IAc、BrAc、SUAN、TNBS、PCMB、DTT等8种化学修饰剂在一定的条件下选择性修饰蔗糖酶,研究烟草蔗糖酶分子中氨基酸侧链基团与酶活性中心的关系.结果表明:PMSF、NBS、PCMB等3种化学修饰剂能显著地抑制酶的活力,而BrAc、IAc、TNBS、SUAN、DTT等对酶的活力影响不大.说明对丝氨酸残基、色氨酸残基和巯基的化学修饰后对酶的活力影响很大,而酶分子中的组氨酸残基及赖氨酸残基不在酶的活性中心,修饰后对酶的活力没有直接影响.

ChemiCal Modification of Invertase from Nicotiana tobacum

The invertase from Nicotiana tobacum (tobacco) fresh leaves were selectively modified by eight chemical reagents such as PMSF, NBS, IAc, BrAc, SUAN, TNBS, PCMB and DTT respectively. It can be found that the enzyme activity was significantly decreased after modification of PMSF, NBS, PCMB, but oppositely the IAc, BrAc, TNBS, SUAN, DTT didn't obviously effect the invertase enzyme activity. Study of the chemical modification demonstrated that the Tryptophan residues, Serine residues and Cysteinyl residues are essential functional groups inside of the invertase active site, at the same time suggested the Histidine residues and Lysine residues are not located in the enzyme active site, and didn't directly effect the enzyme activity.