1.1.99.36 additional information no cofactor: NADPH 1.1.99.36 NADH - 1.1.99.36 NADH 1 mol NADH per mol of enzyme trimer 1.1.99.36 NADH comparison of NADH binding in nicotinoprotein alcohol dehydrogenase and in the conventional alcohol dehydrogenase. Considerable parts of the coenzyme binding in the conventional enzyme are also present in the nicotinoprotein. Alterations in two loop structures affect coenzyme binding and appear to tighten it in the nicotinoprotein model. The positions of residues in a sphere of 3.8 A around the coenzyme template of the nicotinoprotein model reveal the presence of coenzyme interactions additional to those in the conventional structure 1.1.99.36 NADH The NADH absorbance spectrum of nicotinoprotein alcohol dehydrogenase has a maximum at 326 nm. Reduced enzyme-bound pyridine dinucleotide can be reversibly oxidized by acetaldehyde. The fluorescence excitation spectrum for NADH bound to the enzyme has a maximum at 325 nm. Upon excitation at 290 nm, energy transfer from tryptophan to enzyme-bound NADH is negligible. The fluorescence emission spectrum upon excitation at 325 nm for NADH bound to the enzyme has a maximum at 422 nm. The fluorescence lifetime of NADH bound to the nicotinoprotein is very short compared to enzyme-bound NADH complexes, also compared to NADH bound to horse liver alcohol dehydrogenase. The cofactor-protein interaction in the nicotinoprotein alcohol dehydrogenase active site is more rigid and apolar than that in horse liver alcohol dehydrogenase 1.1.99.36 NADH tightly bound, but NDMA-dependent alcohol dehydrogenase is unable to use NAD(P)(H) as cofactors