DNA Cleavage by UVA Irradiation of NADH with Dioxygen via Radical Chain Processes

Citations Over TimeTop 21% of 2006 papers

Abstract

Efficient DNA cleaving-activity is observed by UVA irradiation of an O2-saturated aqueous solution of NADH (β-nicotinamide adenine dinucleotide, reduced form). No DNA cleavage has been observed without NADH under otherwise the same experimental conditions. In the presence of NADH, energy transfer from the triplet excited state of NADH (3NADH*) to O2 occurs to produce singlet oxygen (1O2) that is detected by the phosphorescence emission at 1270 nm. No quenching of 1O2 by NADH was observed as indicated by no change in the intensity of phosphorescence emission of 1O2 at 1270 nm in the presence of various concentrations of NADH. In addition to the energy transfer, photoinduced electron transfer from 3NADH* to O2 occurs to produce NADH•+ and O2•-, both of which was observed by ESR. The quantum yield of the photochemical oxidation of NADH with O2 increases linearly with increasing concentration of NADH but decreases with increasing the light intensity absorbed by NADH. Such unusual dependence of the quantum yield on concentration of NADH and the light intensity absorbed by NADH indicates that the photochemical oxidation of NADH with O2 proceeds via radical chain processes. The O2•- produced in the photoinduced electron transfer is in the protonation equilibrium with HO2•, which acts as a chain carrier for the radical chain oxidation of NADH with O2 to produce NAD+ and H2O2, leading to the DNA cleavage.

Related Papers

• → DETERMINATION OF QUANTUM YIELD OF SINGLET OXYGEN FORMATION BY PHOTOSENSITIZATION(1973)113 cited
• → Note: Measuring instrument of singlet oxygen quantum yield in photodynamic effects(2017)2 cited
• → Temperature effects on the solid-matrix luminescence properties of 4-phenylphenol adsorbed on filter paper(1989)21 cited
• → Comparison of Fluorescence-to-Phosphorescence Quantum Yield Ratios in Solid-Matrix Luminescence as a Function of Temperature(1993)4 cited
• Singlet oxygen quantum yield of α-(8-quinolinoxy) zinc phthalocyanine(2008)