INHIBITION OF S-NITROSATION OF REDUCED GLUTATHIONE IN AEROBIC SOLUTIONS OF NITRIC-OXIDE BY PHOSPHATE AND OTHER INORGANIC ANIONS

Reduced glutathione is nitrosated in aerobic solutions of nitric oxide under physiological conditions; however, the extent of S-nitrosation was found to be dependent on the inorganic anions present. Of nine ani ons tested, the bifunctional anions, arsenate, phosphate, and pyrophos phate (40 mM), inhibited the S-nitrosation reaction from 20 to 40%, wh ereas SO42-, H3BO3, SCN-, NO3-, Cl-, and acetate inhibited this reacti on less than or equal to 15%. A mechanism of inhibition is presented t hat involves the catalytic hydrolysis of N-2,O-3, by the bifunctional anions; however, using [O-18]phosphate as inhibitor, only 10% of the t heoretically produced N2O3 was found to be hydrolyzed to nitrite via t his mechanism as calculated from the loss of O-18 from phosphate. We c onclude that this mechanism accounts for only a minor part of the incr eased inhibition of S-nitrosation by these bifunctional anions. (C) 19 96 Elsevier Science Inc.