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. Author manuscript; available in PMC: 2020 Nov 21.
Published in final edited form as: Cell Chem Biol. 2019 Oct 4;26(11):1515–1525.e4. doi: 10.1016/j.chembiol.2019.09.010

Figure 2. Pre-steady state kinetic analysis of ndSQR-mediated sulfur transfer to CoA.

Figure 2.

(A) Dependence of ndSQR activity on CoA concentration assessed in the coupled assay described under Star Methods. The data represent the mean ± S.D. of three independent experiments, each performed in duplicate. (B) ndSQR (40 μM) in 100 mM potassium phosphate buffer, pH 7.4, was rapidly mixed 1:1 (v/v) with Na2S (80 M) for ~35 msec to form the sulfide-induced CT complex at 675 nm (dashed black line), followed by a second rapid 1:1 (v/v) mixing with CoA (3 mM). Spectral changes associated with CT complex decay in ndSQR and concomitant FAD reduction (red line) were monitored over a period of 3 sec. (C) Comparison of the decay kinetics of the sulfide-induced CT complex in ndSQR with or without mixing with CoA (3 mM) monitored at 675 nm over 3 sec. (D) Dependence of the kobs for sulfide-induced CT complex decay on CoA concentration. The data represent the mean ± S.D. of two independent experiments.