Abstract
An aldehyde reductase catalyzing the NADPH-dependent reduction of D-erythrose 4-phosphate to D-erythritol 4-phosphate was purified from beef liver. It was proved to be homogeneous by polyacrylamide gel electrophoresis, sodium dodecyl sulfate polyacrylamide gel electrophoresis and ultracentrifugation analysis. The enzyme was proved to be a monomeric enzyme and its molecular weight was about 40, 000. The enzyme was able to reduce not only tetroses but also trioses, aromatic aldehydes, D-glucuronate and succinic semialdehyde. Apparent Km-values for aromatic aldehydes were lower than those for tetroses, trioses, D-glucuronate and succinic semialdehyde. Barbiturates and valproate were potent inhibitors of the enzyme and their apparent K1-values were in the range of 80-180 μM. Quercitrin was the most potent inhibitor and its K1-value was about 7 μM. From the viewpoint of substrate specificity and inhibitor sensitivity, it seems that the enzyme belongs to the high-Km type aldehyde reductases.
