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. Author manuscript; available in PMC: 2021 Aug 6.
Published in final edited form as: Biochemistry. 2015 Nov 25;54(48):7098–7109. doi: 10.1021/acs.biochem.5b00994

Figure 4.

Figure 4.

EPR of wt and Y139F Cb H-NOXs with excess NO. Panel A. (a) Reaction of 4.5 μM wt Cb H-NOX with 20 equiv of NO for 1 min, exhibiting EPR signatures of the majority a 5c NO-heme complex plus a minor portion of a 6c NO-heme-His complex. (b) EPR spectrum of a 6c NO-heme-His complex simulated using the following parameters: gx = 2.090, gy = 1.978, gz = 2.005; AN1: Ax = 6 G; Ay = 10 G and Az = 24.0 G; AN2: Ax = 6 G; Ay = 10 G and Az = 7 G. (c) Subtraction of 30% of (b) from (a) yields an EPR spectrum of a pure 5c NO-heme complex. Panel B. (d) Reaction of 6.0 μM Y139F Cb H-NOX reacted with 20 equiv NO for 1 min, exhibiting EPR signatures of the majority a 6c NO-heme-His complex with a minor portion of a 5c NO-heme complex. (e) EPR spectrum of a 5c NO-heme complex simulated using the following parameters: gx = 2.080, gy = 2.035, gz = 2.009; AN: Ax = 18 G; Ay = 20 G and Az = 16.7 G. (f) Subtraction of 30% of (e) from (d) yields an EPR spectrum of a pure 6c NO-heme-His complex.