NADPH-细胞色素P450还原酶的结晶及初步X射线研究。
Crystallization and preliminary x-ray studies of NADPH-cytochrome P450 reductase.
作者信息
Djordjevic S, Roberts D L, Wang M, Shea T, Camitta M G, Masters B S, Kim J J
机构信息
Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226, USA.
出版信息
Proc Natl Acad Sci U S A. 1995 Apr 11;92(8):3214-8. doi: 10.1073/pnas.92.8.3214.
NADPH-cytochrome P450 reductase (CPR; NADPH:ferrihemoprotein reductase, EC 1.6.2.4) catalyzes the transfer of electrons to all known microsomal cytochromes P450. CPR is unique in that it is one of only two mammalian enzymes known to contain both flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), the other being the various isoforms of nitric oxide synthase. Similarities in amino acid sequence and in functional domain arrangement with other key flavoproteins, including nitric oxide synthase, make CPR an excellent prototype for studies of interactions between two flavin cofactors. We have obtained diffraction-quality crystals of rat liver CPR, expressed in Escherichia coli and solubilized by limited proteolysis with trypsin. The crystals were grown in Hepes buffer (pH 7.0), containing polyethylene glycol 4500 and NaCl. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit cell dimensions a = 103.3 A, b = 116.1 A, and c = 120.4 A. If we assume that there are two molecules of the 72-kDa CPR polypeptide per asymmetric unit, the calculated value of Vm is 2.54 A3/Da.
NADPH-细胞色素P450还原酶（CPR；NADPH：铁血红素蛋白还原酶，EC 1.6.2.4）催化电子向所有已知的微粒体细胞色素P450转移。CPR的独特之处在于，它是已知仅有的两种含有黄素腺嘌呤二核苷酸（FAD）和黄素单核苷酸（FMN）的哺乳动物酶之一，另一种是一氧化氮合酶的各种同工型。与包括一氧化氮合酶在内的其他关键黄素蛋白在氨基酸序列和功能域排列上的相似性，使CPR成为研究两种黄素辅因子之间相互作用的优秀模型。我们已经获得了在大肠杆菌中表达并经胰蛋白酶有限度蛋白酶解溶解的大鼠肝脏CPR的衍射质量晶体。晶体在含有聚乙二醇4500和氯化钠的Hepes缓冲液（pH 7.0）中生长。晶体属于正交空间群P2(1)2(1)2(1)，晶胞参数a = 103.3 Å，b = 116.1 Å，c = 120.4 Å。如果我们假设每个不对称单元中有两个72 kDa的CPR多肽分子，Vm的计算值为2.54 Å3/Da。
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