Fluorescence Resonance Energy Transfer Between Coenzyme Nadh And Tryptophan

Fluorescence resonance energy transfer( FRET) between coenzyme nicotinamide adenine dinucleotide (NADH) and tryptophan in different environments were investigated by using time correlation single photon counting technique, combined with UV-Vis absorption and steady-state fluorescence spectroscopy. Single tryptophan, bovine serum albumin (BSA) and lactate dehydmgenase(LDH) were mixed with NADH, respectively, and the spectral data indicated that the energy transfer between tryptophan and NADH occurred only when lactate dehydrogenase was mixed with NADH. Pyruvic acid were added to block the FRET channel between lactate dehydrogenase and NADH, it was verified that the presence of protein-NADH binding sites was a prerequisite for FRET between NADH and tryptophan by time-resolved fluorescence spectroscopy and decay-associated spectra (DAS). Furthermore, the average fluorescence lifetime of tryptophan in lactate dehydrogenase was deceased and it was mainly due to the energy transfer between the tryptophan component with lifetime of tau=7.35 ns and NADH, and the efficiency of energy transfer between NADH and tryptophan was calculated. The results might provide a new idea for further study of the interaction between NADH and proteins.