Table 2.
Misconceptions in graphical representations of electron entry into CI and CII
| CI e-input errors | Ref. | CII e-input errors | Ref. | ||
|---|---|---|---|---|---|
| NADH | → NAD+ + H+ | (45, 97, 99) | FADH2 | → FAD | (4, 23, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99)a |
| NADH | → NAD | (52, 56)b | FADH2 | → FAD | (52, 56)b |
| NAD | → NADH | (56)c | FAD | → FADH2 | (56)c |
| NADH | → NAD+ + H+ | (106, 122, 156, 157, 163, 172, 181) | FADH2 | → FAD | (100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187)d |
| NADH | → NAD | (123, 125, 130, 168, 177, 184) | |||
| NADH +H+ | → NAD+ + 2H+ | (149) | |||
| NADH | → NAD+ + H+ | (227, 238) | FADH2 | → | (188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240)e |
| NADH | → NAD | (220, 227) | |||
| NADP | (240) | ||||
| NADH | → NAD+ + H+ | (241) | FADH2 | → FAD + H+ | (241) |
| NADH | → NAD+ + H+ | (242, 248, 259, 260, 261, 265, 268, 274) | FADH2 | → FAD + 2H+ | (242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280)f |
| NADH | → NAD + H+ | (243, 245, 271, 278) | |||
| NADH | → NAD+ + 2H+ | (244, 246, 247, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 262, 263, 264, 266, 267, 269, 270, 273, 275, 276, 277, 278, 279, 280) | |||
| NADH | → NAD + 2H+ | (272) | |||
| NADH | → NAD | (286) | FADH2 | → FAD+ | (281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310)g |
| NADH +H | → NAD+ | (307) | FADH2 | → FAD+ | (307) |
| NADH | → NAD + H+ | (311) | FADH2 | → FAD+ +H+ | (311) |
| NADH | → NAD+ + H+ | (312) | FADH2 | → FAD+ +H+ | (312) |
| NADH | → NAD+ + H+ | (313, 315, 316, 318) | FADH2 | → FAD+ +2H+ | (313, 314, 315, 316, 317, 318, 319) |
| NADH | → NAD+ + 2H+ | (314, 317, 319) | FADH2 | → FAD+ +2H+ | |
| FADH2 | → FAD2+ | (320) | |||
| NADH + H+ | → NADH | (321) | FADH2 | → FADH | (321, 322, 323, 324, 325, 326, 327, 328, 329) |
| NADH | → NAD | (326) | |||
| NADH | → NAD+ + H+ | (330) | FADH2 | → FADH +H+ | (330) |
| FADH2 | → FADH+ | (331, 332)h | |||
| FADH | → | (333, 334) | |||
| NADH | → NAD + H+ | (335, 336) | FADH | → FAD | (335, 336) |
| FADH | → FAD+ | (337, 338, 339) | |||
| NADH | → NAD+ + H+ | (340) | FADH | → FAD+ + H+ | (340) |
| NADH | → NAD+ + H+ | (341) | FADH | → FAD+ + 2H+ | (341) |
| FADH+ | → FAD | (342) | |||
| FAD | → FADH2 | (343, 344, 345)i | |||
| FAD+ | → FADH2 | (346) | |||
| FADH2 | → FAD + 2H+ | (347)j | |||
| FADH2 | → CI → CII | (348) | |||
| ETF | → CII → CIII | (349, 350, 351, 352, 353, 354, 355)k | |||
| NADH | → NAD+ + H+ | (241) | CI | → CII → CIII | (129, 166, 171, 176, 183, 223, 241, 339, 348, 373) |
| NAD+ + H+ | → NADH | (386)l | |||
2{H+ + e-} is donated to CI in the oxidation NADH + H+ → NAD+ + 2{H+ + e-}, and to CII in the oxidation Succinate2- → Fumarate2- + 2{H+ + e-}.
FAD a substrate of SDH and FADH2 a substrate of CI (Fig. 3, A–C).
Oxidation by CI and CII of NADH and FADH2, respectively, from the TCA cycle.
Reduction by CI and CII of NAD (NAD+) and FAD from β-oxidation.
Figure 3, D and E.
Figure 3F.
Figure 3, G and H.
Figure 3I.
Figure 3J.
Electron transfer into the Q-junction does not occur from a common FADH2 pool from CII and CGpDH, as Fig. 6 of ref. (345) suggests, but through functionally separate branches converging at the Q-junction.
Paradoxically, oxidation of FADH2 is linked to oxidation of succinate with formation of FAD and fumarate and 2H+; Succinate + FADH2 → FAD + Fumarate + 2H+.
The pathway is either shown from β-oxidation to CII or explicitly from ETF to CII (Fig. 5).
Fig. 7 of ref. (386) shows reduction of NAD+ by CI, where it should be oxidation of NADH.