一种来自大肠杆菌的新型肽基脯氨酰顺/反异构酶。

A novel peptidyl-prolyl cis/trans isomerase from Escherichia coli.

作者信息

Rahfeld J U, Schierhorn A, Mann K, Fischer G

机构信息

Max-Planck-Gesellschaft, Arbeitsgruppe Enzymologie der Peptidbindung, Halle/Saale, Germany.

出版信息

FEBS Lett. 1994 Apr 18;343(1):65-9. doi: 10.1016/0014-5793(94)80608-x.

DOI:10.1016/0014-5793(94)80608-x

PMID:8163020

Abstract

A novel peptidyl-prolyl cis/trans isomerase was isolated from Escherichia coli cell extract and characterized partially. Determination of the molecular mass by electrospray mass spectrometry indicated a protein of 10102 +/- 2 Da, smaller than cyclophilins or FK 506 binding proteins currently known. The specificity constant kcat/Km determined with Succinyl-Ala-Xaa-Pro-Phe-4-nitroanilide (Xaa = Leu) had a value comparable to those from cyclophilins from the same organism. However, the pattern of subsite specificity (Xaa = Gly, Ala, Val, Ile, Leu, Phe, Trp, His, Lys and Glu) was reminiscent of FK506 binding peptidyl-prolyl cis/trans isomerases. The enzyme activity was not inhibited by cyclosporin A or FK506 at inhibitor concentrations of < 5 microM, concentrations that affect most bacterial peptidyl-prolyl cis/trans isomerases. Computer-assisted analysis of 21 amino acid residues of the N-terminus determined by Edman degradation revealed no homology to known peptidyl-prolyl cis/trans isomerases.

摘要

从大肠杆菌细胞提取物中分离出一种新型肽基脯氨酰顺反异构酶，并对其进行了部分特性鉴定。通过电喷雾质谱法测定分子量，结果表明该蛋白分子量为10102±2 Da，比目前已知的亲环蛋白或FK506结合蛋白小。用琥珀酰 - 丙氨酸 - Xaa - 脯氨酸 - 苯丙氨酸 - 4 - 硝基苯胺（Xaa = 亮氨酸）测定的特异性常数kcat/Km与来自同一生物体的亲环蛋白的值相当。然而，亚位点特异性模式（Xaa = 甘氨酸、丙氨酸、缬氨酸、异亮氨酸、亮氨酸、苯丙氨酸、色氨酸、组氨酸、赖氨酸和谷氨酸）让人联想到FK506结合肽基脯氨酰顺反异构酶。在抑制剂浓度<5 microM时，该酶活性不受环孢菌素A或FK506的抑制，而这种浓度会影响大多数细菌肽基脯氨酰顺反异构酶。通过埃德曼降解法对N端的21个氨基酸残基进行计算机辅助分析，结果显示与已知的肽基脯氨酰顺反异构酶无同源性。