Table 1. Effective Electron Transfer Rates^a.

syringe 1	syringe 2	effective electron transfer rate (s–1)
2Fd, reduced	MMOH	76.1 ± 1.3
2Fd, reduced	MMOH–2MMOB	17.0 ± 0.7
2Fd, reduced	MMOH–2MMOB–0.5MMOR	18.3 ± 0.8
2NADH	MMOH–2MMOR	14.0 ± 0.4
2NADH	MMOH–2MMOB–2MMOR	3.52 ± 0.31

^aElectron transfer reactions were initiated by mixing the reagent in syringe 1 with protein(s) in syringe 2 in single-mixing stopped-flow experiments (setups also shown in Figures 6a and 7a).