Skip to main content
. Author manuscript; available in PMC: 2019 Feb 7.
Published in final edited form as: Biochemistry. 2017 Feb 7;56(7):986–996. doi: 10.1021/acs.biochem.6b01093

Figure 4.

Figure 4

Effect of glutathione concentration on the rate of SQOR-catalyzed reduction of CoQ1 in the absence or presence of H2S. Glutathione:CoQ reductase activity is measured in the absence of H2S in 100 mM potassium phosphate buffer, pH 7.5, containing 2.84 nM SQOR, 80 μM CoQ1, 0.0036% Tween20, and 90 μM EDTA at 25 °C. The observed rate of CoQ1 reduction was corrected for the contribution due to nonenzymic reactions. Line 1 was generated by a linear regression analysis (r2 = 0.9416) of the corrected data (blue circles). H2S oxidation with glutathione as sulfane sulfur acceptor is measured in the presence of saturating H2S (200 μM) under otherwise identical conditions. The observed rate of CoQ1 reduction was corrected for the contribution due to the glutathione:CoQ reductase reaction and nonenzymic reactions. Curve 2 was obtained by fitting a 3-parameter hyperbola [v = v0 + kcat [GSH]/(Km + [GSH]) (r2=0.9873)] to the corrected data (red circles).