CONTRIBUTION OF ACIDIC ADH(CLASS III) TO ALCHOL METABOLISM

酸性 ADH（III 类）对酒精代谢的贡献

• 批准号: 04454231
• 负责人: HASEBA Takeshi
• 金额: $ 0.64万
• 依托单位: NIPPON MEDICAL SCHOOL
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04454231/
• 关键词: Mouse; Alcohol dehydrogenase; Class I ADH; Class III ADH; Solution hydrophobicity; Activity regulation; Alcohol metabolism; Intracellular hydrophobicity; ClassIおよびIIIADH; 疎水物質; マイクロダイアリシス法

(1) A fraction of acidic alcohol dehydrogenase (Class III ADH) activity of the mouse liver corresponded to 10-42% that of basic ADH (Class I) known as a key enzyme in alcohol metabolism in vivo, when ethanol was used as a substrate at concentrations of blood level (15-100 mM).(2) The activity of acidic ADH was enhanced with the increase in hydrophobicity of the reaction solution. This activation was due to a marked increase of the catalytic efficiency (Kcat/Km), based on a marked decrease of the Km for ethanol. On the other had, the activity of basic ADH was strongly depressed with the increase in the solution hydrophobicity.(3) Acidic ADH was found to localize mainly in the sinusoidal endothelial cells of the mouse liver, whereas basic ADH was shown to distribute within the cytoplasmic matrix of hepatocytes. Staining the liver tissues with a hydrophobic probe (Nile red) showed that the cytoplasm was hydrophobic, and moreover, the intracelluar hydrophobicity was higher in the sinusoida … More l cells than in the parenchymal cells. These results suggest that intracellular acidic ADH activity was highted, whereas the basic ADH activity was lowered by the effects of intracellular hydrophobicity, compared with their activities measured by the conventional in vitro method.(4) Class III ADH was found in the liver of a so-called "ADH^-" deermouse that possessed a capacity of alcohol metabolism more than 50% that of a "ADH^+" strain. A class of ADH which "ADH^-" strain was genetically deficient in was identified as class I.(5) The contributions of basic ADH and catalase to the total alcohol metabolism in the mouse were estimated to be about 50% and 20%, respectively, by additional administration of specific inhibitors (capronamide for basic ADH and aminotriazole for catalase) after ethanol administration at a dose of 3.0 g/kg (i. p.). The total metabolism was almost completely depressed by adminstration of 4-methylpyrazole, which inhibited not only class I ADH, but also class III ADH and catalase pathway. Taken together with the results from in vitro studies, the alcohol metabolism accounting for about 30% of the total one, which was independent to class I ADH and catalase, was suggested to be due to acidic ADH.Thus, it was concluded that acidic ADH (Class III) may play an important role in alcohol metabolism in vivo and the contributions of the two major ADHs (Class I and III) to the metabolism were reversely regulated in response to the intracellular hydrophobicity. Less

(1)当以乙醇为底物时，小鼠肝脏酸性乙醇脱氢酶(Class III ADH)活性相当于体内乙醇代谢关键酶碱性ADH(Class I)的10~42%。(2)随着反应液疏水性的增加，酸性ADH活性增强。这种活化是由于乙醇的Km显著降低，从而显著提高了催化效率(Kcat/Km)。碱性ADH活性随溶液疏水性的增加而强烈抑制。(3)酸性ADH主要定位于肝窦内皮细胞，碱性ADH主要分布于肝细胞胞质基质中。用疏水探针(尼罗红)对肝组织进行染色，发现细胞质是疏水的，而且…的细胞内疏水性更高实质细胞中L细胞多于实质细胞。这些结果表明，在细胞内疏水性的影响下，细胞内酸性ADH活性升高，而碱性ADH活性降低。(4)在一种所谓的“ADH^-”鹿鼠的肝脏中发现了III型ADH，其酒精代谢能力是“ADH^+”的50%以上。(5)小鼠酒精灌胃3.0g/kg乙醇后加用特异性抑制剂(碱性ADH的卡普罗胺和过氧化氢酶的氨基三唑)，估计碱性ADH和过氧化氢酶对小鼠总酒精代谢的贡献率分别约为50%和20%。给予4-甲基吡唑后，细胞总代谢几乎完全受抑，不仅抑制I类ADH，而且还抑制III类ADH和过氧化氢酶途径。结合体外实验结果，推测乙醇代谢是由酸性ADH引起的，且与I类ADH和过氧化氢酶无关，约占总ADH的30%。因此，酸性ADH(III类)可能在体内乙醇代谢中起重要作用，并且两种主要ADH(I类和III类)对代谢的贡献受细胞内疏水性的反向调节。较少

项目成果

Haseba, T., Yamamoto, I., Ohono, Y.and Uedaira, H.: "Effect of hydrophobicity of organic compounds on activities of alcohol dehydrogenase isozymes (Class I and III)." Proceedings of 6th Eur. Cong. Biotec.vol.III. WE066 (1993)

Haseba, T.、Yamamoto, I.、Ohono, Y. 和 Uedaira, H.：“有机化合物的疏水性对乙醇脱氢酶同工酶（I 类和 III 类）活性的影响”。

Yamamoto, I., Haseba, T., Kurosu, M.and Watanabe, T.: "Allosterism of acidic alcohol dehydrogenase (Class III) of mouse liver and its role in alcohol metabolism." J.Nippon Med. Sch.59(2). 38-46 (1992)

Yamamoto, I.、Haseba, T.、Kurosu, M. 和 Watanabe, T.：“小鼠肝脏酸性乙醇脱氢酶（III 类）的变构及其在酒精代谢中的作用。”

山本伊佐夫: "マウスAcidic alcohol dehydrogenase(Class III)蛋白の活性調節とそのアルコール代謝における意義" 日本医大誌. 59(2). 38-46 (1992)

Isao Yamamoto：“小鼠酸性乙醇脱氢酶（III 类）蛋白的活性调节及其在酒精代谢中的意义”，日本医科大学杂志 59（2）（1992）。

Haseba,Takeshi: "Effects of hydrophobicity of organic compounds on activities of alcohol dehydrogenase isozymes(Class I and III)." Proceedings of 6th European Congress on Biotechnology.Vol III. WE066 (1993)

Haseba，Takeshi：“有机化合物的疏水性对乙醇脱氢酶同工酶（I 类和 III 类）活性的影响。”

Haseba,Takeshi: "Effects of hydrophobicity of organic compounds on activities of alcohol dehydrogenase isozymes." Proceedings of 6th European Congress on Biotechnology.Vol III. WE066- (1993)

Haseba，Takeshi：“有机化合物的疏水性对乙醇脱氢酶同工酶活性的影响。”