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Reduction of the metallochromic indicators arsenazo III and antipyrylazo III to their free radical metabolites by cytoplasmic enzymes
Author(s) -
Moreno Silvia N.J.,
Mason Ronald P.,
Docampo Roberto
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)81076-0
Subject(s) - hypoxanthine , xanthine oxidase , chemistry , cytosol , xanthine , metabolite , radical , biochemistry , enzyme
At a concentration much lower than that usually employed for measuring cytosolic ionized Ca 2+ concentrations, arsenazo III underwent a one‐electron reduction by rat liver cytosolic fraction or a hypoxanthinexanthine oxidase system to produce an azo anion radical metabolite. NADH, NADPH, N 1 ‐methylnicotinamide, hypoxanthine, and xanthine, in that order, could serve as a source of reducing equivalents for the production of this free radical by the cytosolic fraction. The steady‐state concentration of the azo anion radical and the arsenazo III‐stimulated O 2 consumption were enhanced by calcium and magnesium. Antipyrylazo III was ineffective in increasing O 2 consumption by rat liver cytosolic fraction and gave a much weaker ESR signal of an azo anion radical with both the liver cytosolic fraction, in the presence of NADH, and the hypoxanthine‐xanthine oxidase system.