Free-radical generation by copper ions and hydrogen peroxide. Stimulation by Hepes buffer.
Hydroxyl radicals (OH.), generated by a phosphate-buffered Cu2+/H2O2 system, were detected by lucigenin-amplified chemiluminescence, deoxyribose degradation and benzoate hydroxylation. In each system the buffer, Hepes, was found to stimulate radical generation significantly. There are two main reasons for this effect: Hepes increases Cu2+ solubility in phosphate-buffered systems, and forms a complex with Cu2+ that is effective in generating OH. from H2O2. Pipes, a structurally similar buffer, and histidine, a known Cu2+ chelator, were found to have a similar effect. These data suggest that the crucial factor in such free-radical-generating systems is the availability of Cu2+, and that these actions of Hepes should be considered in the design of studies utilizing such systems.
Simpson
J A
JA
Department of Biology and Biochemistry, Brunel University, Uxbridge, U.K.
Cheeseman
K H
KH
Smith
S E
SE
Dean
R T
RT
D001565:Benzoates / Q000378:metabolism; D019817:Benzoic Acid; D003300:Copper / Q000378:metabolism*; D003855:Deoxyribose / Q000378:metabolism; D005609:Free Radicals; D006531:HEPES / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D006900:Hydroxylation; D008163:Luminescent Measurements; D010879:Piperazines / Q000494:pharmacology*; D013268:Stimulation, Chemical
D001565:Benzoates; D005609:Free Radicals; D010879:Piperazines; D003855:Deoxyribose; D003300:Copper; D019817:Benzoic Acid; D006861:Hydrogen Peroxide; D006531:HEPES