摘要
测得果菠萝蛋白酶是由单亚基组成,分子量约为30k,pl为4.6,每个酶分子含一个游离疏基和二个硫硫键,甲醇、乙醇、乙二醇对酶活力有明显的抑制作用,甲醇、乙醇表现为非竞争性,乙二醇为竞争性,其抑制常数分别为:20％、16.5％和11％。在有机溶剂作用下,监测荧光(332nm)强度随时间的变化过程,作为变性的指标,测定酶在不同浓度有机溶剂中的变性动力学,并按邹氏法测定酶的失活动力学,对酶构象及催化活力关系进行比较,酶的失活速度大于变性速度,说明酶活性中心处于对有机溶剂较敏感的区域,酶的变性与失活过程均可分为快、慢两相的一级反应,这意味着可能存在着部分活力的中间态。
Studies on fruit brometain demonstrated that the enzyme is a mono subunit molecule. Its molecular weight is about 30,000. isoelectric point, 4. 6. The enzyme contains one free sulfhydryl group and two disulfide bonds. The enzyme activity is inhibited distinctly by methanol, ethanol and ethylene glycol. The inhibition by raethanol and ethanol was 'non-competitive' ,but 'competitive' by ethylene glycol. The inhibition constants of the three organic solvents were determined to be 20% , 16. 5% and 11% . respectively. The denaturation and inactivation rate constants of the enzyme in different concentration of organic solvents have been measured. The rate constants of inactivation were larger than those of denaturation. The result indicates that the active site of the enzyme is sensitive to the organic solvents, and that the expression of the enzyme activity is dependent to a great degree on the stability and integrity of the enzyme conformation. It was noted that denaturation and inactivation of the enzyme by organic solvents were composed of two stages: the fast and the slow phases, suggesting that an intermediate transition with partial activity may be present in the system.
出处
《厦门大学学报（自然科学版）》
CAS
CSCD
北大核心
1993年第1期88-93,共6页
Journal of Xiamen University：Natural Science
基金
国家自然科学基金
关键词
果菠萝蛋白酶
有机溶剂
变性
Fruit bromelain. Organic solvents, Denaturation and inactivation. Kinetics
