Yokota A, Haga S, Kitaoka S
Biochem J. 1985 Apr 1;227(1):211-6. doi: 10.1042/bj2270211.
Euglena mitochondria contain both glyoxylate reductase (NADP+) and glycollate dehydrogenase to constitute the glycollate-glyoxylate cycle [Yokota & Kitaoka (1979) Biochem. J. 184, 189-192]. Euglena glyoxylate reductase (NADP+) was purified and its submitochondrial location was determined in order to elucidate the cycle. The purified glyoxylate reductase was homogeneous on polyacrylamide-gel electrophoresis. Difference spectra of the purified enzyme revealed that the enzyme was a flavin enzyme. The Mr of the enzyme was 82 000. The enzyme was specific for NADPH, with an apparent Km of 3.9 microM, and for glyoxylate, with an apparent Km of 45 microM. It was 30% as active with oxaloacetate as with glyoxylate. NADH and hydroxypyruvate did not support the activity at all. The optimum pH was 6.45. Submitochondrial fractionation of purified mitochondria showed that the enzyme was located in the intermembrane space and loosely bound to the outer surface of the inner membrane. These properties and the submitochondrial localization of NADPH-glyoxylate reductase facilitate the operation of the glycollate-glyoxylate cycle in combination with glycollate dehydrogenase, which is tightly bound to the inner membrane of Euglena mitochondria.
眼虫线粒体含有乙醛酸还原酶（NADP+）和乙醇酸脱氢酶，以构成乙醇酸-乙醛酸循环[横田和北冈（1979年）《生物化学杂志》184卷，189 - 192页]。为了阐明该循环，对眼虫乙醛酸还原酶（NADP+）进行了纯化，并确定了其亚线粒体定位。纯化后的乙醛酸还原酶在聚丙烯酰胺凝胶电泳上呈均一性。纯化酶的差示光谱表明该酶是一种黄素酶。该酶的相对分子质量为82000。该酶对NADPH具有特异性，表观Km为3.9微摩尔，对乙醛酸具有特异性，表观Km为45微摩尔。它对草酰乙酸的活性是对乙醛酸活性的30%。NADH和羟基丙酮酸根本不支持该活性。最适pH为6.45。对纯化线粒体进行亚线粒体分级分离表明，该酶位于膜间隙，松散地结合在内膜外表面。NADPH-乙醛酸还原酶的这些性质和亚线粒体定位，与紧密结合在眼虫线粒体内膜上的乙醇酸脱氢酶一起，有助于乙醇酸-乙醛酸循环的运行。
