Fig. 8.

(A) Superimposed spectra of four well-known nitrosothiols (a) CysNO, (b) S-nitrosocysteamine (CANO), (c) S-nitrosoglutathione (GSNO), and (d) nitrosothiol of penicillamine (SNAP). Three of them nearly have the same ε at 545 nm. The observed separation in the absorbances of these three at 545 nm is due to staggering of the time lag before acquiring the spectrum. (B) The effect of glutathione (GSH) on the stability of CANO in a pH 7.4 phosphate buffer. All experimental traces have [CA]₀ = 0.03 mol/L, [NO₂⁻]₀ = 0.03 mol/L, and [H⁺]₀ = 0.05 mol/L. (a) [GSH] = 0, (b) [GSH] = 0, (c) [GSH] = 0.01 mol/L, (d) [GSH] = 0.02 mol/L, (e) [GSH] = 0.03 mol/L, and (f) [GSH] = 0.05 mol/L. Traces a and b are controls. Trace a has no EDTA. Trace b is the same as trace a with 10 μmol/L of EDTA. There is no significant difference between traces a and b, indicating that the water used for preparing reagent solutions did not contain enough trace metal ions to affect the kinetics. Ten microlitres of EDTA was added to