Question

Help with B. and C. please.

4.) (a.) ( 3pts) T = 298 K: Calculate AE® and AG" for the following reaction: 4Cytochrome (Fe) + O2+ 4H-4Cytochrome (Fe) + 2H20 Cytochrome c(Fe 3) + e - Cytochrome c(Fe 2) Eº = 0.254 V Donor 1/202 +2e +2H-H2O E' = 0.815 V Acceptor AE°) = 0.815 V-o.a54V) = 0.561V AG") = -2(96.5)(0.561 V) = -108.273 kJ/mol (b.) (2 pts) What enzyme catalyzes the above reaction? (c.) (3 pts) It takes 20 kJ/mol to pump a proton out the of the matrix into the inner membranes space. Under standard conditions how many protons are pumped into the inner membrane space for every 4 electrons passed on to Oz?

Answer 1

b) The enzyme catalyzing the oxidation of Cytochrome c (Fe²⁺) to cytochrome c (Fe³⁺) in reaction:

4Cytochrome c (Fe²⁺) + O₂ + 4H⁺ ===> 4Cytochrome c(Fe³⁺) + 2H₂O

is cytochrome oxidase.

c) For the reaction

1/2O₂ +2e^- + 2H⁺ ==> H₂O

It is evident that two electrons required to be accepted by the oxygen for 2 protons to be pumped.

Hence under standard conditions for every 4 electrons passed on to the Oxygen (O₂) 4 protons (H⁺) are needed to be pumped in to inter-membrane space from matrix.