内切酶xhoI部分氨基酸残基的化学修饰

限制性核酸内切酶xho I能够被巯基试试剂和修饰赖氨酸、精氨酸残基的试剂抑制,酶的抑制作用遵守假一级动力学,底物λ-DNA对酶的抑制作用有强烈地保护作用,这些资料表明xho Ⅰ含有对酶活性至关重要的必须的赖氨酸残基、精氨酸残基和巯基。

Initial Studies on Chemical Modification of Several Amino Acid Residues of Restriction Endonuclease Xho I

Restriction endonuclease XhoI can be inactivated by some specific protein inhibitors. XhoI is sensitive not only to sulfhdryl reagents but also to the reagents that modify lysine and arginine residues. Inactivation of the enzyme obeyed pseudo-first-order kinetics and resulted in complete elimination of catalysis. Substrate X-DNA strongly protected against inactivation by the reagents. These data suggest that XhoI has essential lysinly residues, arginyl residues and SH groups which are crucial to the enzymatic activity.