摘要
溶液介电常数对天然酶和修饰酶的活性影响不同,天然酶随介电常数增加而酶活性下降,修饰酶则反之,这表明静电相互作用在铜锌超氧化物歧化酶(Cu·Zn-SOD)与超氧阴离子(-O_2^(·-))反应过程中起着重要作用,酶分子活性中心附近ε-NH_3^+为O_2^(·-)进入活性中心提供静电吸引力。在有机溶剂中,SOD的构象会发生变化,从而导致酶活性降低。实验还表明,Cl^-对SOD有明显的抑制作用。
The activity of Cu. Zn-SOD decreases with the increasing ionic strength, which seems that the interaction between superoxide anion and enzyme is promoted by the positive charge on the lysine residues, presumably at vicinity of the active site. The static electric interaction plays an important role in the enzyme reaction.But when the dielectric constant of the medium is decreassd by adding organic solvent,the conformation of SOD changes into a less active form thus the enzyme activity is decreased. It is very interesting that Cl- inhibits the Cu. Zn-SOD specifically.
基金
国家自然科学基金
关键词
超氧物歧化酶
铜
锌
溶液介电常数
Superoxide dismutase
Modified SOD
Dielectric constant
