Vlasuk G P, Ghrayeb J, Ryan D E, Reik L, Thomas P E, Levin W, Walz F G
Biochemistry. 1982 Feb 16;21(4):789-98. doi: 10.1021/bi00533a033.
The multiplicity of phenobarbital-induced cytochromes P-450 in live microsomes from male rats was investigated by using two-dimensional gel electrophoresis, peptide fingerprinting, and immunoaffinity chromatography. Two colonies each of Holtzman and Long-Evans rats were studied. Four molecular forms of phenobarbital-induced cytochromes P-450 were distinguished as polypeptides (designated PB3, variant PB3, PB4, and PB5) which showed apparent immunochemical identity and greater than or equal to 95% fingerprint homology. Two of these polypeptides corresponded to cytochrome P-450b [Ryan, D., Thomas, P. E., Korzeniowski, D., & Levin, W. (1979) J. Biol. Chem. 254, 1365-1374] and cytochrome P-450e [Ryan, D., & Levin, W. (1981) Fed. Proc., Fed. Am. Soc. Exp. Biol. 40, 1640] which had been purified from Long-Evans rats (variant PB3 and PB5, respectively). Each rat colony was characterized by unique combinations of two or three of these immunochemically related forms of cytochromes P-450. Cytochrome P-450e was present in rats from all four colonies, but cytochrome P-450b was only found in Long-Evans rats. Polypeptide PB3 was only found in the two colonies of Holtzman rats, whereas polypeptide PB4 was present in one colony each of Holtzman and Long-Evans rats. In addition to these forms of cytochrome P-450, rats from each colony also evidenced three other major phenobarbital-induced polypeptides which gave unique fingerprints, and one of these was identified as representing epoxide hydrolase. Proteolytic digestion studies of intact microsomes demonstrated that the four immunochemically identical forms of cytochrome P-450 were partially exposed on the outer (cytoplasmic) surface of microsomes. However, polypeptide PB3 was characterized by the greatest rate of proteolytic degradation. These results clearly demonstrate that phenobarbital-induced cytochromes P-450 include microheterogeneous proteins which show remarkable variations related to rat strains and/or colony.
利用二维凝胶电泳、肽指纹图谱和免疫亲和色谱法，对雄性大鼠肝微粒体中苯巴比妥诱导的细胞色素P-450的多样性进行了研究。研究了霍尔茨曼大鼠和朗-埃文斯大鼠各两个群体。苯巴比妥诱导的细胞色素P-450的四种分子形式被鉴定为多肽（分别命名为PB3、变异型PB3、PB4和PB5），它们表现出明显的免疫化学同一性和大于或等于95%的指纹同源性。其中两种多肽分别对应于从朗-埃文斯大鼠中纯化得到的细胞色素P-450b[瑞安，D.，托马斯，P.E.，科尔泽尼奥夫斯基，D.，&莱文，W.（1979）《生物化学杂志》254，1365 - 1374]和细胞色素P-450e[瑞安，D.，&莱文，W.（1981）《联邦程序，美国实验生物学会联合会会刊》40，1640]（分别为变异型PB3和PB5）。每个大鼠群体都以细胞色素P-450的这些免疫化学相关形式中的两种或三种的独特组合为特征。细胞色素P-450e存在于所有四个群体的大鼠中，但细胞色素P-450b仅在朗-埃文斯大鼠中发现。多肽PB3仅在霍尔茨曼大鼠的两个群体中发现，而多肽PB4在霍尔茨曼大鼠和朗-埃文斯大鼠的各一个群体中存在。除了这些细胞色素P-450形式外，每个群体的大鼠还显示出另外三种主要的苯巴比妥诱导的多肽，它们具有独特的指纹图谱，其中一种被鉴定为环氧化物水解酶。完整微粒体的蛋白水解消化研究表明，细胞色素P-450的四种免疫化学相同形式部分暴露于微粒体的外（细胞质）表面。然而，多肽PB3的蛋白水解降解速率最快。这些结果清楚地表明，苯巴比妥诱导的细胞色素P-450包括微异质性蛋白质，它们在大鼠品系和/或群体方面表现出显著差异。
