THE REACTION OF S-NITROSOGLUTATHIONE WITH SUPEROXIDE (VOL 244, PG 525, 1998)

The nitric oxide (NO)-dependent S-nitrosation of thiols to generate S- nitrosothiols has been proposed as an important pathway for the metabo lism of NO in vivo. Although it has been suggested that these S-nitros ated compounds are resistant to decomposition by reactive oxygen metab olites (ROMs), very little information is available regarding the inte raction between S-nitrosothiols and ROMs. We found that S-nitrosogluta thione (GSNO) rapidly reacted with O-2(-) to generate glutathione disu lfide and equimolar quantities of nitrite and nitrate. The reaction wa s second order with respect of GSNO and first order with respect of O- 2(-) with a rate equation of -d[GSNO]/dt = 2k(3)[GSNO](2)[O-2(-)], whe re k(3) = 3 - 6 X 10(8) M-2 s(-1). In addition, the reaction of GSNO w ith O-2(-) generated a strong oxidant as an intermediate capable of ox idizing dihydrorhodamine in the absence of the apparent generation of NO, We conclude that O-2(-) may act as a physiological modulator of S- nitrosation reactions by directly promoting the decomposition of S-nit rosothiols. (C) 1998 Academic Press.