摘要
本文用扫描电子显微技术结合 ＤＮＳ法测定卵磷脂－纤维素酶－水（ＰＣ－Ｃｅｌ－Ｈ２Ｏ）体系中纤维素酶三组分（内切葡聚糖酶，外切葡聚糖酶，β－葡萄糖苷酶）的活性，分析体系中各组分间相互作用，并由此建立起一个模型，用于描述 ＰＣ－Ｃｅｌ－Ｈ２Ｏ 中纤维素酶的作用机理：当 Ｃｐｃ 很小时，极性头部作用于内切葡聚糖酶，使其构象变化，并通过后者抑制了另二种酶的活性；当增大到一定浓度（当Ｃｃｅｌ为０．１３ｍ ｇ／ｍ ｌ时，此 Ｃｐｃ 为０．３ｍ ｇ／ｍ ｌ）时，ＰＣ 的作用使内切葡聚糖酶完全失活，并开始以非极性尾部作用于外切葡聚糖酶；当大于ＰＣ 的临界胶束浓度时，外切酶随非极性部位进入胶束或脂双层而失活，内切葡聚糖酶却因ＰＣ对其作用的变小而部分恢复活性。
Throught determining the activities of three elements (1,4\|β\|D\|glucan glu\|canohydrolase or endo\|1,4\|β\|D\|glucanase, EC3.2.1.4, abbreviation is EG;1,4\|β\|D\|glucan cellobiohydrolase or exo\|1,4\|β\|D\|glucanase, EC3.2.1.91, abbreviation is CBH;β\|1,4\|glucosidase,EC3.2.1.21, abbreviation is BG) of cellulase in PC\|Cel\|H\-2O solution by SEM and the method of DNS,and measureing the interaction of the elements in these solutions, we establish a model to describe the mechanism of actionof cellulase. When Cpc is very small, the PC's polar head affects EG,and restains the activities of the other two enzymes by changing EG's structure;when Cpc increases to a certain concentration (Ccel is 0.13mg.ml -1 ,Cpc is 0.3mg.ml -1 ),EG loses the activity completely because of the action of PC, and PC begin to affect CBH by its nonpolar chains;when Cpc is bigger than CMC of PC,CBH loses its activity with PC's nonpolar chains entering micelles or the lipid bilayer, in the same time EG regains partly its activity because the action of PC becomes weaker.BG has activity in the latter two situations.
出处
《电子显微学报》
CAS
CSCD
1999年第6期584-589,共6页
Journal of Chinese Electron Microscopy Society
关键词
纤维素酶
卵磷脂
酶活性
cellualse
phosphatidalcholine(PC)
activity
