Unfolding and Inactivation During Thermal Denaturation of Aminoacylase  

作　　者：何飚 严明 张彤 周海梦 

出　　处：《Chinese Science Bulletin》1994年第13期1122-1127,共6页

摘　　要：Many researchers have compared inactivation with conformational changes of a number of enzymes during denaturation by guanidine hydrochloride and urea. The results obtained show that inactivation occurs before noticeable conformational change of the enzyme molecule as a whole can be detected. The inactivation rate constantsMany researchers have compared inactivation with conformational changes of a number of enzymes during denaturation by guanidine hydrochloride and urea[1-4]. The results obtained show that inactivation occurs before noticeable conformational change of the enzyme molecule as a whole can be detected. The inactivation rate constants of enzymes were compared to their rate constants of conformational changes under the same denaturation conditions. The results clearly show that the inactivation rates are markedly faster than the rates of conformational changes. Therefore, Tsou suggested that the active sites of some enzymes are located in the limited and flexible molecular regions, and this flexibility may be essential for the catalytic activity of these enzymes[5]. Recently the result observed provides direct evidence of the flexibility of the active site of the enzyme[6]. However, previously the comparison was made only between inactivation and conformational changes of non-metal enzymes. The activity changes accompanying the courses of conformational changes during denaturation of metal enzyme were seldom discussed. What are the roles of metal ion in the enzyme-catalyzed reaction and the folding of this protein? Aminoacylase (EC 3.5.1.14) is dimeric, consisting of two identical subunits, each with an active site[7]. It is similar to the creatine kinase in the molecular weight and association of subunits. Zn2+ located at the active site is essential for the enzyme activity[8]. In this note, the inactivation and conformational changes of aminoacylase during thermal denaturation are studied. The results obtained show that inactivation occurs before significant conformational changes of aminoacylase, and the inactivation rates of the enzyme are much faster than those of conformational changes.

关 键 词：AMINOACYLASE THERMAL DENATURATION INACTIVATION unfolding. 

分 类 号：Q7[生物学—分子生物学]