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首页> 美国卫生研究院文献>Biochemical Journal >Purification and characterization of a novel NADPH(NADH)-dependent glyoxylate reductase from spinach leaves. Comparison of immunological properties of leaf glyoxylate reductase and hydroxypyruvate reductase.
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Purification and characterization of a novel NADPH(NADH)-dependent glyoxylate reductase from spinach leaves. Comparison of immunological properties of leaf glyoxylate reductase and hydroxypyruvate reductase.

机译：菠菜叶中新型NADPH（NADH）依赖性乙醛酸还原酶的纯化和表征。叶片乙醛酸还原酶和羟基丙酮酸还原酶的免疫学特性比较。

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摘要

A novel reductase displaying high specificity for glyoxylate and NADPH was purified 3343-fold from spinach leaves. The enzyme was found to be an oligomer of about 125 kDa, composed of four equal subunits of 33 kDa each. A Km for glyoxylate was about 14-fold lower with NADPH than with NADH (0.085 and 1.10 mM respectively), but the maximal activity, 210 mumol/min per mg of protein, was similar with either cofactor. Km values for NADPH and NADH were 3 and 150 microM respectively. Optimal rates with either NADPH or NADH were found in the pH range 6.5-7.4. The enzyme also showed some reactivity towards hydroxypyruvate with rates less than 2% of those observed for glyoxylate. Results of immunological studies, using antibodies prepared against either glyoxylate reductase or spinach peroxisomal hydroxypyruvate reductase, suggested substantial differences in molecular structure of the two proteins. The high rates of NADPH(NADH)-glyoxylate reductase in crude leaf extracts of spinach, wheat and soya bean (30-45 mumol/h per mg of chlorophyll) and its strong affinity for glyoxylate suggest that the enzyme may be an important side component of photorespiration in vivo. In leaves of nitrogen-fixing legumes, this reductase may also be involved in ureide breakdown, utilizing the glyoxylate produced during allantoate metabolism.
机译：从菠菜叶片中纯化了对乙醛酸和NADPH具有高特异性的新型还原酶3343倍。发现该酶是约125kDa的寡聚体，由每个33kDa的四个相等的亚基组成。用NADPH测得的乙醛酸酯的Km值比用NADH测得的Km值低约14倍（分别为0.085和1.10 mM），但任一种辅因子的最大活性为210 mgmol / min / mg蛋白质。 NADPH和NADH的Km值分别为3和150 microM。在pH范围6.5-7.4中发现使用NADPH或NADH的最佳速率。该酶还显示出对羟基丙酮酸的一些反应性，其速率低于乙醛酸酯的2％。使用针对乙醛酸还原酶或菠菜过氧化物酶体羟基丙酮酸还原酶制备的抗体进行的免疫学研究结果表明，这两种蛋白的分子结构存在实质性差异。在菠菜，小麦和大豆的粗叶提取物中，NADPH（NADH）-乙醛酸还原酶的比率很高（每毫克叶绿素为30-45μmol/ h），并且对乙醛酸的亲和力强，表明该酶可能是重要的副成分体内的光呼吸作用。在固氮类豆科植物的叶子中，该还原酶也可能利用尿囊酸酯代谢过程中产生的乙醛酸酯参与尿素的分解。

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