Study of tissue-specific dihydrodiol dehydrogenase

二氢二醇脱氢酶（Dihydrodiol dehydrogenase， DD, EC 1.3.1.20）是一种催化芳烃反式二氢二醇依赖nadp氧化的酶，已被证明与芳烃的细胞毒性有关。这种酶在哺乳动物组织中以多种形式存在。在多种形式的DD中，二聚体是组织特异性表达的，但其结构和生理功能尚未阐明。本研究旨在阐明二聚体DD的结构、与功能的关系及其可能的临床意义。对所得结果进行了总结。猴肾、猪和狗肝脏中的二聚体DD与nadp依赖性d -木糖脱氢酶（EC 1.1.1.179）相同。通过对兔晶状体、人肠道及上述动物组织中二聚体DDs的蛋白测序和cDNA克隆，发现该酶与葡萄糖-果糖氧化还原酶等原核蛋白组成了一个新的蛋白家族。对猴二聚体DD的定点诱变表明，tir -180是一个催化残基，Lys-97和His-79同时参与了该反应的辅酶结合和化学步骤，tir -71和His-76参与了辅酶结合。此外，Trp-125、Asp-176和Trp-254被认为与底物结合有关，在三个残基中，Asp-176被认为对醇底物适应结合位点很重要。晶体学的研究正在进行中。二聚体DD可被几种药物抑制，如非甾体抗炎药，其中有效抑制剂通常具有4-羟基苯基酮结构。该酶的mRNA虽然在正常人肾脏中未检测到，但在五个肾癌标本中的一个中检测到。关于外显子4区域的变异基因未检测到，对于其他外显子区域的研究将继续寻找临床意义。在克隆二聚体基因组基因的过程中，我注意到该基因包含在19号染色体的工作草图序列中。该基因的5'-非编码区含有多种转录因子的推测结合位点。本研究的结构和功能方面的结果发表在10^< >国际羰基代谢酶学和分子生物学研讨会（New Mixico，美国，2000年7月）。少

Dihydrodiol dehydrogenase (DD, EC 1.3.1.20), which catalyzes the NADP-dependent oxidation of trans-dihydrodiols of aromatic hydrocarbons, has been shown to be involved in cytotoxicity of the aromatic hydrocarbons. The enzyme exits in multiple forms in mammalian tissues. Of the multiple forms dimeric DD is tissue-specifically expressed, but its structure and physiological function have not been elucidated. This study was performed to elucidate the structure of dimeric DD, its relationship to the function and possible clinical significance. The results obtained are summarized.1. Dimeric DD in monkey kidney, pig and dog liver was demonstrated to be identical with NADP-dependent D-xylose dehydrogenase (EC 1.1.1.179).2. The protein sequencing and/or cDNA cloning primary structures of dimeric DDs in rabbit lens, human intestine and the above animal tissues revealed that the enzymes constitute a new protein family with prokaryotic proteins including glucose-fructose oxidoreductase.3. The site … More -directed mutagenesis on the monkey dimeric DD suggested that Tyr-180 is a catalytic residue, Lys-97 and His-79 function both coenzyme binding and chemical steps of the reaction, and Tyr-71 and His-76 are involved in coenzyme binding. In addition, Trp-125, Asp-176 and Trp-254 were suggested to be responsible for substrate binding, and of the three residues Asp-176 is thought to be important for the adaptation of the alcohol substrate in to the binding site. The crystallographic study is now in progress.4. Dimeric DD was inhibited by several drugs such as nonsteroidal anti-inflammatory agents, of which the potent inhibitors commonly had 4-hydroxyphenylketone structure. The enzyme's mRNA, although it did not detected in normal human kidney, was detected in one of five renal cancer specimen. The variant gene with respect to exon 4 region was not detected, and such a study for other exon regions will be continued to find clinical significance.5. During the course of cloning of the genomic gene for dimeric, I noticed that the gene is included in a working draft sequence of chromosome 19. The 5'-noncoding region of this gene contains various putative binding sites for transcription factors.6. The structural and functional aspects obtained in this study was presented in 10^<th> International Symposium on Enzymology and Molecular Biology of Carbonyl Metabolism (New Mixico, U.S.A., July, 2000). Less