Purification and properties of NADPH-dependent aldehyde reductase from human liver.
An aldehyde reductase (EC 1.1.1.2) from human liver has been purified to homogeneity. The enzyme is NADPH-dependent, prefers aromatic to aliphatic aldehydes as substrates, and is inhibited by barbiturates and hydantoins. The following physicochemical parameters were determined: molecular weight, 36,200; sedimentation coefficient, 2.9 S; Stokes radius, 2.65 nm; isoelectric point, pH 5.3; extinction coefficient at 280 nm, 54,300 M-1 cm-1. Results from polyacrylamide gel electrophoresis with and without sodium dodecyl sulfate, gel filtration, and ultracentrifugation suggest a monomeric structure. On molecule of NADPH binds to the enzyme causing a red shift of the coenzyme absorption maximum from 340 to 352 nm. The amino acid composition has been determined and a partial specific volume of 0.74 was computed from these data. An alpha-helicity of 7 and 18% was estimated from the ellipticities at 208 and 222 nm, respectively. Combination of the most reactive thiol group with p-mercuribenzoate does not cause loss of catalytic activity. Inactivation occurs when more than one thiol group is modified. The presence of NADPH or NADP+ prevents loss of activity by thiol modification. The comparison of structural features of aldehyde reductase with other monomeric and oligomeric dehydrogenases suggest similarities of aldehyde reductase with octopine dehydrogenase.
D000429:Alcohol Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism; D000447:Aldehydes / Q000378:metabolism*; D000596:Amino Acids / Q000032:analysis; D002942:Circular Dichroism; D005260:Female; D006801:Humans; D006827:Hydantoins / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D008970:Molecular Weight; D009249:NADP / Q000378:metabolism; D010634:Phenobarbital / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D013053:Spectrophotometry
D000447:Aldehydes; D000596:Amino Acids; D006827:Hydantoins; D011720:Pyrazoles; D009249:NADP; D000429:Alcohol Oxidoreductases; D010634:Phenobarbital