von Bahr-Lindström H, Höög J O, Hedén L O, Kaiser R, Fleetwood L, Larsson K, Lake M, Holmquist B, Holmgren A, Hempel J
Biochemistry. 1986 May 6;25(9):2465-70. doi: 10.1021/bi00357a026.
Two cDNA clones for human liver alcohol dehydrogenase (ADH) were identified, together covering 1450 nucleotides that contain the cDNA sequence of the ADH1 locus and include a coding region of 1122 nucleotides for the alpha subunit of the enzyme. In parallel, direct peptide analyses of the carboxymethylated protein also established most of the amino acid sequence. Nucleotide and peptide data were in complete agreement and show exchanges at 24 positions in the alpha relative to the beta subunit. One of the cDNA clones had a 139-nucleotide internal deletion at a position of possible interest in relation to mRNA processing, ancestral connections, or DNA replication. The structure of the alpha subunit is homologous to that of the beta and gamma subunits but has many exchanges, also of functionally important residues, explaining the different enzymatic properties. In total, 35 of 374 amino acid residues differ between the class I isozymes, and the substitutions add an extra SH group in the alpha subunit. Only in the beta-pleated sheet region of the coenzyme-binding domain is almost complete lack of substitutions noted, illustrating the importance of this region. In contrast, the active site region is far less conserved. However, similar exchanges of functional significance have also been found in distantly related alcohol and polyol dehydrogenases.
鉴定出了两个人类肝脏乙醇脱氢酶（ADH）的cDNA克隆，它们总共覆盖1450个核苷酸，其中包含ADH1基因座的cDNA序列，并且包括该酶α亚基的1122个核苷酸的编码区。同时，对羧甲基化蛋白的直接肽分析也确定了大部分氨基酸序列。核苷酸和肽数据完全一致，显示α亚基相对于β亚基在24个位置存在交换。其中一个cDNA克隆在与mRNA加工、祖先联系或DNA复制可能相关的位置有一个139个核苷酸的内部缺失。α亚基的结构与β和γ亚基的结构同源，但有许多交换，包括功能重要的残基，这解释了不同的酶学性质。I类同工酶中总共374个氨基酸残基中有35个不同，这些取代在α亚基中增加了一个额外的SH基团。仅在辅酶结合域的β折叠区域几乎完全没有取代，这说明了该区域的重要性。相比之下，活性位点区域的保守性要低得多。然而，在远缘相关的醇脱氢酶和多元醇脱氢酶中也发现了具有功能意义的类似交换。
