RT Journal Article
SR Electronic
T1 S-Transnitrosation Reactions Are Involved in the Metabolic Fate and Biological Actions of Nitric Oxide
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 526
OP 534
VO 284
IS 2
A1 Zhenguo Liu
A1 M. Audrey Rudd
A1 Jane E. Freedman
A1 Joseph Loscalzo
YR 1998
UL http://jpet.aspetjournals.org/content/284/2/526.abstract
AB S-Nitrosothiols are a group of potent, bioactive compounds that form through the reaction of nitric oxide (NO) with thiols in the presence of oxygen. These compounds are naturally occurring in vivo, stabilize NO and potentiate its biological effects. S-Nitrosoglutathione is the most abundant intracellular S-nitrosothiol, and the kinetics for its formation favors de novosynthesis. In this analysis, we studied the formation of S-nitrosothiols by S-transnitrosation, or exchange of -NO for -H between sulfur atoms; we synthesized S-nitroso-glutathionyl-Sepharose 4B beads (SNO-4B) as a reagent with which to measure S-transnitrosation reactions. We detected a maximum of 1.57 ± 0.24 pmol NO/bead (n = 5) after S-nitrosation of the beads with acidified nitrite. The stability of the S-NO bond was dependent on temperature, but not pH over the 5 to 9 range (except at pH 9 at 37°), with an estimated t1/2 of 30 hr at 22°C and of approximately 2 wk at 4°C. We demonstrated that SNO-4B transfers -NO to glutathione and to cysteine rapidly and in a pH-dependent manner. The initial rate of transfer of -NO from SNO-4B to glutathione at room temperature was 0.53, 3.03 and 5.14 μM/min at pH 5.0, 7.4 and 9.0, respectively (P < .05). Under the same conditions, the initial rate of -NO transfer to cysteine was 0.72, 3.71 and 4.69 μM/min at pH 5.0, 7.4 and 9.0, respectively (P < .05). There was no appreciable S-transnitrosation between SNO-4B and bovine serum albumin. We further demonstrated that SNO-4B evokes significant vasodilator and platelet inhibitory responses in plasma-free systems and activates platelet soluble guanylyl cyclase. These data suggest a mechanism by which to explain the metabolic fate and distribution of NO among thiol pools in the vasculature, and implicate S-transnitrosation at the cell surface in NO signal transduction. The American Society for Pharmacology and Experimental Therapeutics