乙腈对菜蓟（Cynara cardunculus L.）中卡多辛A稳定性的影响。

Effect of acetonitrile on Cynara cardunculus L. cardosin A stability.

作者信息

Shnyrova Anna V, Oliveira Claudia S, Sarmento Ana C, Barros Marlene T, Zhadan Galina G, Roig Manuel G, Shnyrov Valery L

机构信息

Departamento de Bioquímica y Biología Molecular, Universidad de Salamanca, Salamanca, Spain.

出版信息

Int J Biol Macromol. 2006 Nov 15;39(4-5):273-9. doi: 10.1016/j.ijbiomac.2006.04.007. Epub 2006 Apr 27.

DOI:10.1016/j.ijbiomac.2006.04.007

PMID:16712922

Abstract

The kinetics of the structural changes affecting cardosin A, a plant aspartic proteinase (AP) from Cynara cardunculus L., in the presence of a mixture of acetonitrile (AN) in water (W) was studied. Incubation of cardosin A with 10% (v/v) AN resulted in a gradual increase in protein helicity, accompanied by changes in the tertiary structure, seen by changes in the intrinsic fluorescence of tryptophan. Differential scanning calorimetry (DSC) revealed that the temperature of denaturation of cardosin A decreased upon the addition of AN. With longer incubation times, the small chain of cardosin A denatured completely, consequent exposure of the single tryptophan residue accounting well for the observed spectral shift intrinsic fluorescence of the protein. Enzymatic activity assays demonstrated that the kinetically determined unfolding of the small chain of cardosin A does not result in loss of the activity of this enzyme.

摘要

研究了在水（W）中加入乙腈（AN）混合物的情况下，影响来自刺菜蓟（Cynara cardunculus L.）的植物天冬氨酸蛋白酶（AP）——卡多辛A结构变化的动力学。卡多辛A与10%（v/v）的AN孵育导致蛋白质螺旋度逐渐增加，同时三级结构发生变化，这可通过色氨酸内在荧光的变化看出。差示扫描量热法（DSC）显示，加入AN后卡多辛A的变性温度降低。随着孵育时间延长，卡多辛A的小链完全变性，单个色氨酸残基的暴露很好地解释了所观察到的蛋白质内在荧光光谱位移。酶活性测定表明，动力学测定的卡多辛A小链的去折叠不会导致该酶活性丧失。