Xu D P, Washburn M P, Sun G P, Wells W W
Department of Biochemistry, Michigan State University, Michigan 48824, USA.
Biochem Biophys Res Commun. 1996 Apr 5;221(1):117-21. doi: 10.1006/bbrc.1996.0555.
A GSH-dependent dehydroascorbate reductase (EC 1.8.5.1) was purified to homogeneity from human erythrocytes. The enzyme was a monomer of 32 kDa and was purified 133-fold from a crude DEAE-Sepharose fraction with a 25% yield. The reduced protein had a pI of 5.1 as judged by isoelectric focusing. Kinetic analysis gave a Kcat of 316 min-1, a Km of 0.21 mM for DHA with a Kcat/Km of 2.47 x 10(4) M-1 sec-1, and a Km of 3.5 mM for GSH with a Kcat/Km of 1.51 x 10(3) M-1 sec-1. This is the second DHA reductase (after thioltransferase) isolated from human erythrocytes, but unlike thioltransferase, it has no thiol-disulfide oxido-reductase activity.
从人红细胞中纯化出一种依赖谷胱甘肽的脱氢抗坏血酸还原酶（EC 1.8.5.1），使其达到同质状态。该酶是一种32 kDa的单体，从粗制的DEAE - 琼脂糖组分中纯化了133倍，产率为25%。通过等电聚焦判断，还原态蛋白质的pI为5.1。动力学分析得出，催化常数（Kcat）为316 min⁻¹，对脱氢抗坏血酸（DHA）的米氏常数（Km）为0.21 mM，催化效率（Kcat/Km）为2.47×10⁴ M⁻¹ s⁻¹，对谷胱甘肽（GSH）的Km为3.5 mM，Kcat/Km为1.51×10³ M⁻¹ s⁻¹。这是从人红细胞中分离出的第二种DHA还原酶（继硫醇转移酶之后），但与硫醇转移酶不同的是，它没有硫醇 - 二硫键氧化还原酶活性。
