Evidence for functional and structural multiplicity of pregnenolone-16 alpha-carbonitrile-inducible cytochrome P-450 isozymes in rat liver microsomes.
Evidence for functional and structural multiplicity of pregnenolone-16 alpha-carbonitrile-inducible cytochrome P-450 isozymes in rat liver microsomes.
复制标题
大鼠肝微粒体中孕烯醇酮 16 α-腈诱导的细胞色素 P-450 同工酶功能和结构多样性的证据。
DOI：
10.1021/bi00387a022
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发表时间：
1987
期刊：
影响因子：
2.9
通讯作者：
Halpert,J
中科院分区：
文献类型：
--
作者：
Graves,PE;Kaminsky,LS;Halpert,J
摘要：给成年雌性大鼠注射孕烯醇酮-16a-碳腈（PCN）导致肝微粒体细胞色素P-450总量增加2倍，4种体外单加氧酶活性增加5-7倍，被认为是诊断PCN诱导的主要细胞色素P-450同工酶。然而，在给pcn处理的大鼠给予氯霉素后，这些单加氧酶活性可以分解为三组。因此，微粒体将三乙酰齐兰霉素转化为与还原血红素铁形成光谱复合物的代谢物的能力降低了80%。（/?）的转化率仅下降了50%。-华法林转化为9,10 -脱水代谢，雄烯二酮的6/3-羟基化速率。更引人注目的是(/?)-warh的10-羟基化。通过氯霉素治疗，它实际上提高了2倍。对pcn处理的成年雄鼠的肝微粒体进行了分离研究，回收了两种高纯度的细胞色素sp -450，称为PCNa和PCNb。发现PCNb的前15个氨基酸残基序列与PCNb诱导的同工酶相同，其完整的氨基酸序列最近已在另一个实验室推断出来[Gonzalez， F. J., Nebert， D. W., Hardwick， J. P., & Kasper, CB (1985) J. Biol.]。另一个同工酶，PCNa，在PCNb的前15个位置中有3个氨基酸序列不同。经免疫印迹分析，PCNb多克隆抗体也能识别PCNa。因此，pcn诱导的大鼠肝细胞色素p -450家族包括至少两个独立的蛋白质。
Revised Manuscript Received February 24, 1987 abstract: Administration of pregnenolone-16a-carbonitrile (PCN) to adult female rats causec a 2-fold increase in total liver microsomal cytochrome P-450 along with 5-7-fold increases in four in vitro mono-oxygenase activities considered diagnostic for the major PCN-inducible cytochrome P-450 isozyme. However, upon administration of chloramphenicol to PCN-treated rats, these monooxygenase activities could be resolved into threegroups. Thus, the ability of the microsomes to convert triacetyloleandomycin to a metabolite that forms a spectral complex with the reduced heme iron was decreased by 80% bychloramphenicol, whe’’. as only a 50% decrease was observed in the rate of conversion of (/?)-warfarin to its 9, 10-dehydro metabc te and in the rate of 6/3-hydroxylation of androstenedione. More strikingly, the 10-hydroxylation of (/?)-warh. in was actually enhanced 2-fold by the chloramphenicol treatment. Fractionation studies were carried out on liver microsomes from PCN-treated adult malerats, and two highly purified cytochromesP-450, referred to as PCNa and PCNb, were recovered. PCNb was found to be identical in the sequence of the first 15 amino acid residues with a PCN-inducible isozyme, the complete amino acid sequence of which has recently been deduced in another laboratory [Gonzalez, F. J., Nebert, D. W., Hardwick, J. P., & Kasper, CB (1985) J. Biol. Chem. 260, 7435-7441], The other isozyme, PCNa, differed in amino acid sequence in three of the first 15 positions from PCNb. Upon immunoblot analysis, polyclonal antibodies raised to PCNb also recognized PCNa. Thus, the PCN-inducible family of rat liver cytochrome P-450comprises at least two separate proteins.