Structure-activity correlations in human kidney aldehyde reductase-catalyzed reduction of para-substituted benzaldehyde by 3-acetyl pyridine adenine dinucleotide phosphate.
Steady-state kinetic parameters of the human kidney aldehyde reductase-catalyzed reduction of para-substituted benzaldehydes by 3-acetyl pyridine dinucleotide phosphate (3-APADPH) were determined. The kcat of aldehyde reduction by 3-APADPH was 2- to 4-fold lower than by NADPH. The dissociation constant of 3-APADPH from the enzyme-coenzyme complex was higher (77 microM) than that of NADPH (5.3 microM). Primary deuterium kinetic isotope effects on both kcat and kcat/Km for para-substituted benzaldehyde reduction by 3-APADPH (with the exception of para-carboxybenzaldehyde) were equal and on average 2.82 +/- 0.21, suggesting that these reactions follow a rapid equilibrium-ordered reaction scheme in which the hydride transfer step is rate-limiting. Multiple regression analysis of the data suggests that benzaldehyde reduction depends upon electronic substituent effects, characterized by a rho value of 0.5. These data are consistent with a transition state in which the charge on the aldehyde carbonyl increases relative to the charge on this group in the ground state. A positive deviation of para-carboxybenzaldehyde from the linear correlation between other benzaldehydes and the substituent constant sigma + suggests a specific interaction of the carboxyl substituent of the substrate with the enzyme.
Bhatnagar
A
A
Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston 77550.
Liu
S Q
SQ
Srivastava
S K
SK
D000426:Alcohol Dehydrogenase / Q000378:metabolism*; D001547:Benzaldehydes / Q000737:chemistry*; D002384:Catalysis; D006801:Humans; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D009249:NADP / Q000737:chemistry / Q000031:analogs & derivatives; D010084:Oxidation-Reduction; D013329:Structure-Activity Relationship
D001547:Benzaldehydes; C048483:3-acetylpyridine-adenine dinucleotide phosphate; D009249:NADP; D000426:Alcohol Dehydrogenase; C032175:benzaldehyde