CRYSTAL-STRUCTURE AND REFINEMENT OF CYTOCHROME P450(TERP) AT 2-CENTER-DOT-3 ANGSTROM RESOLUTION
CRYSTAL-STRUCTURE AND REFINEMENT OF CYTOCHROME P450(TERP) AT 2-CENTER-DOT-3 ANGSTROM RESOLUTION
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DOI：
10.1016/0022-2836(94)90019-1
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发表时间：
1994-03-04
影响因子：
5.6
通讯作者：
DEISENHOFER, J
中科院分区：
文献类型：
--
作者：
HASEMANN, CA;RAVICHANDRAN, KG;DEISENHOFER, J
细胞色素P450Terp是一种I类(线粒体/细菌)P450，它催化α-松油醇的羟基化，是假单胞菌分解代谢同化该化合物的一部分。从纯化的蛋白质中生长的晶体具有空间群P6 1 2 2的对称性，晶胞尺寸a=b=6 9·4Å，c=45 6·6Å，α=β=90°，γ=12 0°。在康奈尔高能同步加速器上收集了衍射数据，采用分子置换和多种同象置换相结合的方法求解了P450Terp的结构。建立了P450Terp的模型，并针对原始数据进行了改进，对于I≥σ(I)在6？0？和2.3？分辨率之间的数据，R因子为18.9%。该模型包含428个P450 Terp氨基酸残基中的412个；螺旋F和G之间的环在晶体中是无序的。虽然P450Terp的整体折叠与P450cam非常相似，但只有四分之三的C1α位置可以叠加，均方根偏差仅为1.87？可以预测P450 Terp与底物结合的方式，并识别可能的底物接触残基。血红素环境和相邻i-螺旋上的侧链位置暗示了酶催化循环中质子传递的可能方式。
Cytochrome P450 terp is a class I (mitochondrial/bacterial) P450 that catalyzes the hydroxylation of α-terpineol as part of the catabolic assimilation of this compound by a pseudomonad species. Crystals grown from the purified protein have the symmetry of space group P6 1 22, and cell dimensions a= b= 69· 4 A ̊, c= 456· 6 A ̊, α= β= 90°, γ= 120°. Diffraction data were collected at the Cornell High Energy Synchrotron Source, and the structure of P450 terp was solved by a combination of molecular replacement and multiple isomorphous replacement techniques. A model of P450 terp was built and refined against native data, to an R-factor of 18· 9% for data with I≥ σ (I) between 6· 0 Å and 2· 3 Å resolution. This model contains 412 of the 428 P450 terp amino acid residues; the loop between helices F and G is disordered in the crystal. While the overall fold of P450 terp is very similar to that of P450 cam, only three-quarters of the C 1α positions can be superimposed, to a root-mean-square deviation of only 1· 87 Å. The mode of substrate binding by P450 terp can be predicted, and probable substrate contact residues identified. The heme environment and side-chain positions in the adjacent I-helix suggest possible modes of proton delivery in the catalytic cycle of the enzyme.