Multi-NMR and fluorescence spectra study the effects of aluminum(III) on coenzyme NADH in aqueous solutions

The interactions of dihydronicotinamide adenine dinucleotide (NADH) with Al(III) in near neutral aqueous solutions were studied by means of multinuclear (31P, 27Al, 1H and 13C)-NMR and fluorescence spectra techniques. The results suggested that Al(III) interacts with NADH by occupying the binding sites of pyrophosphate oxygen atoms and locks the adenine moiety of coenzyme in an anti folded conformation Meanwhile, the weak attractive interactions ('association') may occur between Al(III) and the hydroxyl groups of ribose rings through the intramolecular hydrogen bonding. Furthermore, at biologically relevant pH and concentrations of Al(III) and NADH (pH 6.5, C(Al)=10(-6)-10(-5) M), Al(III) could increase the amount of folded forms of NADH, which will result in reducing the coenzyme NADH activity in hollow-dehydrogenases reaction systems. However, in the presence of possible competing organic acids such as citrate, oxalate and tartate, could detoxify these Al(III) toxic effect.