Table 2.
Midpoint potentials of human and bovine cytochrome b5 and its site-specific mutants.
| Samples | Midpoint potentials (mV) (vs. SHE) | method | References |
|---|---|---|---|
| HLMWb5 | -3.2 | optical titration | present study |
| HLMWb5 + poly-L-lysine (200 μM) | +16.5 | optical titration | present study |
| human erythrocyte cytochrome b5 | -2 | optical titration | [46] |
| full-length human cytochrome b5 | -2.6 | optical titration | present study |
| full-length human cytochrome b5 | |||
| + poly-L-lysine (200 μM) | +8.7 | optical titration | present study |
| L51I | -9.5 | optical titration | present study |
| L51I + poly-L-lysine (200 μM) | +10.5 | optical titration | present study |
| A59V | -7.7 | optical titration | present study |
| A59V + poly-L-lysine (200 μM) | +11.7 | optical titration | present study |
| A59S | -4.9 | optical titration | present study |
| A59 S + poly-L-lysine (200 μM) | +9.6 | optical titration | present study |
| G67A | -8.4 | optical titration | present study |
| G67A + poly-L-lysine (200 μM) | -2.7 | optical titration | present study |
| G67S | -7.3 | optical titration | present study |
| G67S + poly-L-lysine (200 μM) | +14.2 | optical titration | present study |
| bovine liver cyt. b5 (tryptic fragment) | +5.1 | OTTLE | [49] |
| bovine liver cyt. b5 (tryptic fragment) | -1.8 | OTTLE | [50] |
| bovine liver cyt. b5 (tryptic fragment) | +5 | OTTLE | [44] |
| bovine liver cyt. b5 (tryptic fragment) | |||
| + 20 mM Mg2+ | +15 | OTTLE | [44] |
| bovine liver cyt. b5 (tryptic fragment) | +2 | OTTLE | [24] |
| F35L | -26 | OTTLE | [24] |
| F35H | -49 | OTTLE | [24] |
| F35Y | -64 | OTTLE | [24] |
| rat OM cyt. b5 (soluble domain) | -102 | OTTLE | [25] |
| rat OM cyt. b5 (soluble domain) | |||
| + poly-L-lysine (104 μM) | -70 | OTTLE | [28] |
| rat OM DiMe cyt. b5 (soluble domain) | -36 | OTTLE | [28] |
| rat OM DiMe cyt. b5 (soluble domain) | |||
| + poly-L-lysine (104 μM) | -33 | OTTLE | [28] |
| V61L | -117 | OTTLE | [28] |
| V61L/V45L | -148 | OTTLE | [28] |
| V61I/V45I | -63 | OTTLE | [29] |
Midpoint potentials of human cytochrome b5 (HLMWb5) and its mutants were estimated for the redox titration data obtained in the absence or presence of poly-L-lysine by a least-square curve fitting using the Nernst equation with assuming a single redox component. For a comparative purpose, midpoint potentials for the tryptic fragment of bovine liver cytochrome b5 and OM cytochrome b5 obtained by OTTLE method were presented.
OTTLE, optically-transparent-thin-layer-electrode in the presence of Ru(NH3)6 as a mediator