Molecular properties of p-(dimethylamino)benzaldehyde bound to liver alcohol dehydrogenase: a Raman spectroscopic study

摘要: We have studied the binding nature of an aromatic aldehyde to catalytic site liver alcohol dehydrogenase from horse (LADH) using preresonance Raman spectroscopy. The compound p-(dimethylamino)benzaldehyde (DABA) is converted corresponding in presence nicotinamide adenine dinucleotide (NADH) and a amount enzyme at neutral pH. A stable ternary complex LADH/NADH/DABA can be formed if coenzyme are excess high pH [Jagodzinski, P. W., Funk, G. F., & Peticolas, W. L. (1982) Biochemistry 21, 2193-2202]. obtained spectrum bound DABA by subtracting contribution binary LADH/NADH this complex. In order understand normal mode patterns DABA, four isotopically labeled derivatives were synthesized their spectra, solution complex, measured. Three these compounds contain substitutions functionally important moiety: (i) one such substitution, aldehydic hydrogen atom was replaced deuterium; (ii) another, deuterium, carbon 13C; (iii) third derivative, only 13C. fourth derivative has had two atoms 3- 5-positions ring deuterium atoms. find that many spectral modes fairly extended, involving both stretching bending motions entire molecule, although few quite localized. structure changes considerably when it binds LADH/NADH. As model for we examined zinc complexes (and all samples) anhydrous diethyl ether methylene chloride. striking correspondence between spectra enzyme-bound DABA-Zn found, which extends derivatives. This suggests major roles LADH provide divalent ion form first-sphere Lewis acid data also suggest other interactions with its protein surroundings NADH minor. An estimate carbonyl bond character been made on basis response bands isotopic labeling trends observed solvents various polarities.(ABSTRACT TRUNCATED AT 400 WORDS)