TY - JOUR
T1 - Interaction of nitric oxide with photoexcited rose bengal
T2 - Evidence for one-electron reduction of nitric oxide to nitroxyl anion
AU - Singh, Ravinder Jit
AU - Hogg, Neil
AU - Kalyanaraman, B.
N1 - Funding Information:
The research has been supported by NIH Grants CA49089, HL45048, and RR01008.
PY - 1995/12/20
Y1 - 1995/12/20
N2 - The interaction of nitric oxide (·NO) with Rose Bengal (RB) in the presence of electron donors was investigated. Upon illumination of a mixture of RB and·NO with visible light, an enhancement in the rate of·NO consumption was observed that increased with increasing RB concentration. In the presence of electron donors (NADH, glutathione, or ascorbate), the rates of·NO depletion increased further. NADH enhanced·NO depletion to a greater extent than either glutathione or ascorbate. Photoactivated RB under anaerobic conditions reacts with NADH to form the RB anion radical (RB·—), which has a characteristic visible absorption band centered at 418 nm. Rose Bengal anion radical disproportionates to give RB and a colorless reduced form of RB, RBH—. The net result of this process is the photobleaching of RB. The presence of·NO during irradiation of RB and NADH introduced a lag time into the kinetics of RB photobleaching. The length of this lag time was proportional to the concentration of·NO. A similar lag time, which was also dependent on the·NO concentration, was observed in the kinetics of formation of RB·—. The three-line electron spin resonance (ESR) spectrum of RB·—, with an intensity ratio 1:2:1, was obtained during irradiation of RB and NADH under anaerobic conditions.·NO introduced a concentration-dependent lag time into the kinetics of the appearance of this ESR signal. We propose that·NO oxidizes RB·—to regenerate RB and thus inhibit photobleaching until·NO is consumed. This reaction predicts the formation of NO—, the one-electron reduced form of·NO. Nitrous oxide, a characteristic dimerization product of NO—, was detected by gas chromatography. This evidence indicates the occurrence of a Type I mechanism between photoactivated RB and·NO.
AB - The interaction of nitric oxide (·NO) with Rose Bengal (RB) in the presence of electron donors was investigated. Upon illumination of a mixture of RB and·NO with visible light, an enhancement in the rate of·NO consumption was observed that increased with increasing RB concentration. In the presence of electron donors (NADH, glutathione, or ascorbate), the rates of·NO depletion increased further. NADH enhanced·NO depletion to a greater extent than either glutathione or ascorbate. Photoactivated RB under anaerobic conditions reacts with NADH to form the RB anion radical (RB·—), which has a characteristic visible absorption band centered at 418 nm. Rose Bengal anion radical disproportionates to give RB and a colorless reduced form of RB, RBH—. The net result of this process is the photobleaching of RB. The presence of·NO during irradiation of RB and NADH introduced a lag time into the kinetics of RB photobleaching. The length of this lag time was proportional to the concentration of·NO. A similar lag time, which was also dependent on the·NO concentration, was observed in the kinetics of formation of RB·—. The three-line electron spin resonance (ESR) spectrum of RB·—, with an intensity ratio 1:2:1, was obtained during irradiation of RB and NADH under anaerobic conditions.·NO introduced a concentration-dependent lag time into the kinetics of the appearance of this ESR signal. We propose that·NO oxidizes RB·—to regenerate RB and thus inhibit photobleaching until·NO is consumed. This reaction predicts the formation of NO—, the one-electron reduced form of·NO. Nitrous oxide, a characteristic dimerization product of NO—, was detected by gas chromatography. This evidence indicates the occurrence of a Type I mechanism between photoactivated RB and·NO.
KW - Nitric oxide
KW - Nitrous oxide
KW - Nitroxyl anion
KW - Photosensitization
KW - Rose Bengal
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U2 - 10.1006/abbi.1995.0049
DO - 10.1006/abbi.1995.0049
M3 - Article
C2 - 8554328
AN - SCOPUS:0029584586
SN - 0003-9861
VL - 324
SP - 367
EP - 373
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 2
ER -