Purification and characterization of a glutathione dependent dehydroascorbate reductase from human erythrocytes.
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.
Xu
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Department of Biochemistry, Michigan State University, Michigan 48824, USA.
Washburn
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Sun
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Wells
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WW
D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000201:enzymology*; D054477:Glutaredoxins; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D007525:Isoelectric Focusing; D007700:Kinetics; D010088:Oxidoreductases / Q000097:blood* / Q000302:isolation & purification*; D011490:Protein Disulfide Reductase (Glutathione)
D054477:Glutaredoxins; D010088:Oxidoreductases; D011490:Protein Disulfide Reductase (Glutathione); C020666:glutathione dehydrogenase (ascorbate); D005978:Glutathione