Table 1.

Autoxidation rates of wild-type and distal histidine mutants of cytoglobin and neuroglobin.

Cytoglobin	Rate (min−1)	Neuroglobin	Rate (min−1)
Wild-type	0.270 ± 0.020a	Wild-type	0.23 ± 0.03b
H81A	0.094 ± 0.038	H64A	0.066 ± 0.005b
H81Q	0.019 ± 0.005	H64Q	0.010 ± 0.002b
H81L	0.314 ± 0.043	H64L	0.010 ± 0.004
H81W	0.135 ± 0.034	H64W	0.076 ± 0.006b
R84E	2.362 ± 0.359c
T91D	0.062 ± 0.005
V105Y	0.107 ± 0.018
L108Q	0.116 ± 0.051
K116E	0.366 ± 0.057

Values determined at 37°C in 100 mM sodium phosphate, pH 7.4. All values from this work except

^afrom reference [8] and

^bfrom reference [25].

^cRate constant for the fast phase; R84E decay is best fit to a two-exponential equation; the rate constant for the slower phase is 0.303 ± 0.037 min⁻¹. The fast phase accounts for 73 ± 12% of the decay.