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. 2014 Feb 11;53(8):1284–1295. doi: 10.1021/bi401307r

Figure 1.

Figure 1

Effect of BH4 (A) and BH2 (B) on NO production by Sf9-nNOS. Panel A shows the stimulation by BH4 of NO formation, measured with the oxyHb assay. The curve through the data is the best fit to the Hill equation with fitting parameters EC50 = 2.4 ± 0.6 × 10–7 M, Act0 = 147 ± 8 nmol·mg–1·min–1, Act∞ = 333 ± 9 nmol·mg–1·min–1, h = 1.1 ± 0.3. Panel B shows the inhibition by BH2 in the absence (closed symbols) and presence (open symbols) of 10 μM BH4. The curve through the data in the presence of BH4 is the best fit to the Hill equation with fitting parameters IC50 = (1.3 ± 1.1) × 10–5 M, Act0 = 283 ± 7 nmol·mg–1·min–1, Act∞ = 177 ± 17 nmol·mg–1·min–1, h = 0.5 ± 0.2. Experimental conditions: 2 μg/mL (∼13 nM) Sf9-nNOS, 0.2 mM Arg, 0.2 mM NADPH, 5 μM FAD, 5 μM FMN, 10 μg/mL CaM, 0.5 mM CaCl2, 5 μM oxyHb, 1000 U/mL SOD, 50 mU/mL CAT, 0.2 mM CHAPS, 0.1 mM EDTA, 50 mM TEA (pH 7.4), and pteridines as indicated at 37 °C. Data points are presented ± SEM (n = 3).