Biliverdin-IXα还原酶和βBiliverdin-IX还原酶从人类肝脏。纯化和表征。
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山口T, Komoda Y,中岛以H
Biliverdin-IXα还原酶和βBiliverdin-IX还原酶从人类肝脏。纯化和表征。
生物化学杂志。1994年9月30日,269 (39):24343 - 8。
- PubMed ID
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7929092 (在PubMed]
- 文摘
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这份报告首次描述了四种形式的识别胆绿素还原酶包括两个biliverdin-IXβ还原酶和两个biliverdin-IXα还原酶,指定的同功酶I和II和同功酶III和IV,分别在人类肝脏胞质分数。四种形式的胆绿素还原酶纯化同质性。有一个7800 - 15000倍增加在特定活动相比,原油的准备,和复苏8 - 26%。纯化酶是单体的分子量约21000(同功酶I和II)和34000(同功酶III和IV)。胆绿素的酶是严格具体和纯化未发现其他氧化还原酶的活动准备。纯化酶用NADPH和NADH作为电子给体的胆绿素还原。明显的Km值同功酶I, II, III, IV NADPH的35.9,13.1,10.9,和34.1 microM,分别而NADH分别为5.6,8.2,7.9,和23.4毫米。假设NADPH而不是NADH生理捐赠者的细胞内减少胆绿素。同功酶的表观公里价值I和II NADPH biliverdin-IXβ的系统是0.3 microM而同功酶III和IV microM biliverdin-IXα是1.0和0.8,分别。同功酶I和II使用biliverdin-IXβ,第九γ,和第九三角洲基质但不是biliverdin-IXα,α和同功酶III和IV首选biliverdin-IX作为最有效的衬底在四个胆绿素同分异构体。NADPH-dependent酶活性被抑制基质浓度超过3 - 4 microM。 The NADPH-dependent enzyme activities, especially isozymes III and IV, were sensitive to SH reagents including iodoacetamide, p-chloromercuribenzoic acid, and N-ethylmaleimide. The optimum pH of the reaction with NADPH for isozymes I and II was 8.2 whereas that for isozymes III and IV was 7.4. The proportion of the total activity of isozymes I and II to that of isozymes III and IV was considerably higher in the fetal than in the adult liver.