Optical and biochemical properties of NADH irradiated by high peak power Q-switched ruby laser or by low power C.W. HeNe laser

Abstract

The effect of irradiation with non-linearly absorbed light on reduced nicotinamide-adenine-dinucleotide (NADH) by either high peak power Ruby laser or by low-power c.w. HeNe laser has been examined. The two-photon absorption process (TPA) by NADH has been demonstrated for Ruby laser irradiation and the cross-section measured for NADH. The irradiation by both Ruby or HeNe laser produces modifications in the spectra of absorbance and fluorescence of NADH. It has been shown that the presence of NADH, irradiated by both lasers, decreases the activity of the lactate dehydrogenase in an anticompetitive manner and this is measured by using pyruvate as a substrate. These results give clear evidence that the absorption process by NADH induces changes in the biochemical behaviour of the coenzyme and this could be considered as a mechanism through which intracellular activity can be modified by laser energy.