Bovine lens aldehyde reductase (aldose reductase). Purification, kinetics and mechanism.

Aldehyde reductase (aldose reductase) was purified to homogeneity (as judged by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis) from bovine lens by affinity chromatography on NADP+-Sepharose. The enzyme, a monomer of Mr about 40000, was active with a variety of alpha- hydroxyketones , including fructose. The minimum degree of the rate equation was 2:2 in the case of DL-glyceraldehyde, but linear kinetics were observed for glucose and NADPH over the concentration range studied. The enzyme largely followed a ternary-complex mechanism, with initial binding of NADPH before glucose and final release of NADP+.