Hydrogen Sulfide Abrogates Hemoglobin-Lipid Interaction in Atherosclerotic Lesion

Figure 6

Reactions of ferrylHb with sulfide. (a, left and right panels) Representative UV-vis spectra of 4 μmol/L metHb (black line), reaction of 4 μmol/L metHb with 8 μmol/L H₂O₂ after 400 s (red line) and reaction of 4 μmol/L ferrylHb with 100 μmol/L sulfide after an additional 60 s (blue line). Arrows indicate wavelength values where the kinetic runs were recorded. (b, left panel) Representative stopped-flow kinetics traces for the reaction of 4 μmol/L ferrylHb with 100 μmol/L sulfide at 406 nm (circles) and 425 nm (squares) and the corresponding double exponential fits (solid lines). (b, right panel) Sulfide concentration dependencies of the obtained pseudo-first-order rate constants from the double exponential fits of the stopped-flow kinetic traces (λ = 425 nm). MetHb (4 μmol/L) was reacted with H₂O₂ (8 or 20 μmol/L) in the presence of sulfide (100–700 μmol/L). The faster (circles) and slower (squares) reactions represent reactions of the ferryl moieties of the alpha and beta chains, respectively. Data points and error bars represent the average and standard deviations of 4 independent experiments. (c, left panel) Representative stopped-flow kinetics traces for the reaction of 4 μmol/L ferrylHb with 100 μmol/L sulfide at 620 nm (blank circles) and the corresponding double exponential fit (solid lines). (c, right panel) Sulfide concentration dependence of the pseudo-first-order rate constant for the reaction of ferrylHb with sulfide from the double exponential fits of the kinetic traces, where ferrylHb was generated in the reaction of 8 μmol/L metHb with 40 μmol/L H₂O₂ in the first mixing cycle of a sequential stopped-flow experiment, followed by mixing with sulfide solutions in a 1 : 1 ratio in the second mixing cycle after a 240 s delay time. The faster (circles) and slower (squares) reactions represent the reactions of the ferryl moieties of the alpha and the beta chains, respectively. Data points and error bars represent the average and standard deviations of 3 independent experiments.

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