摘要
中华猕猴桃蛋白酶(Actinidin)在盐酸胍溶液中活力变化结果提示:酶在0.1mol/L胍中活力略有升高,随胍浓度增大,活力先经历一个陡降区,在1—2mol/L胍中有个稳定区域,随胍浓度增大,活力继续下降。同时以荧光光谱,圆二色光谱研究该酶分子的构象变化。结果表明引起酶构象发生明显变化所需胍浓度(3mol/L)远比酶明显失活所需胍浓度(0.5mol/L)大。相同胍浓度下酶活力丧失速度快于构象变化速度。经5mol/L胍变性的酶直接稀释至胍浓度为0.05mol/L时,酶活力不能恢复,而构象迅速恢复。失活酶先稀释至胍浓度为1—2mol/L、再进一步稀释至胍浓度为0.05mol/L,活力能恢复50％左右。以上结果表明,相对于整个酶分子来说,活性中心的构象变化对变性剂更敏感。Actinidin的失活及复活过程是多相的复杂过程。
The activity of Actinidin after incuLation in different concentrations of GuHCl has been determined. 50% activity was lost in Imol/L GuHCl. Between l-2mol/L GuHCl, a region of relatively small activity change continued, followed by an activity decrease with increasing GuHCl concentration. The changes of activity and conformation of Actinidin in GuHCl have been cnmpared.lt was shown that inactivation of the enzyme occured at a lower concentration than that required to bring about a significant conformational change of the molecule as indicated by CD and fluorescence spectra. The rate constants for conformational changes were slower than the inactivation rate constants. The reactivation and refolding of GuHCl denatured Actinidin have been studied.When the denatured enzyme solution was diluted to 0.05mol/L GuHCl, the fluorescence quickly restored to λ max of the native slate, whereas the activity showed no sign of recovery.The above results suggest that the active site of Actinidin is more flexible than the molecule as a whole.
出处
《生物物理学报》
CAS
CSCD
北大核心
1992年第3期527-531,共5页
Acta Biophysica Sinica
关键词
盐酸胍
折叠
中华猕猴桃
蛋白酶
Actinidin, Gu·HCl, inactivation reactivation, unfolding, folding.
