Edwards K J, Ollis D L, Dixon N E
Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia.
J Mol Biol. 1997 Aug 15;271(2):258-65. doi: 10.1006/jmbi.1997.1151.
The structure of the unliganded form of the Escherichia coli cytoplasmic peptidyl-prolyl isomerase (ppiB gene product) in a new crystal form was determined by the molecular replacement method and refined to an R-factor of 16.1% at 2.1 A resolution. The enzyme crystallized in the orthorhombic C2221 space group with unit cell dimensions of a=44.7 A, b=68.2 A and c=102.0 A. Comparison with the reported structure of the enzyme complexed with the tripeptide substrate succinyl-Ala-Pro-Ala-p-nitroanilide revealed subtle changes that occur upon complex formation. There is evidence to suggest that two surface loops have significantly reduced mobility in the complexed structure.
通过分子置换法确定了大肠杆菌细胞质肽基脯氨酰异构酶（ppiB基因产物）未结合配体形式的新晶体结构，并在2.1埃分辨率下精修至R因子为16.1%。该酶在正交晶系C2221空间群中结晶，晶胞参数为a = 44.7埃，b = 68.2埃，c = 102.0埃。与报道的该酶与三肽底物琥珀酰 - 丙氨酸 - 脯氨酸 - 丙氨酸 - 对硝基苯胺形成的复合物结构进行比较，发现复合物形成时发生了细微变化。有证据表明，在复合物结构中两个表面环的流动性显著降低。
