<prompt> Which complex in mitochondrial ETC does not pump out H ions ?Complex IComplex IIComplex IIIComplex IV  <response>: Complex II Complex II does not act as proton H pump.Complex I: NADH CoQ-reductase Permit ATP formation Site I Act as proton pumpComplex II: Succinate Co rcductase No ATP formComplex CoQ - cytochrome - C reductase Permit ATP formation Site II Act as proton pumComplex IV: Cytochrome C oxidase Permit ATP formation Site III Act as proton pump 