Electron Transport Chain General Information

 

          Takes place in inner mitochondrial membrane

 

          Follows Krebs Cycle in aerobic metabolism

 

          Energy released to make ATP

 

          Requires series of oxidation-reduction reactions

 

          Requires four membrane-bound complexes

 

          3 ATP produced per NADH

 

          2 ATP produced per FADH2

 

          ATP production:

 

               NADH per glucose: 2 from glycolysis + 8 from Krebs

                cycle = 30 ATP

              

               FADH2 per glucose: 2 from Krebs cycle = 4 ATP

             

              2 ATP per glucose from glycolysis + 2 GTP from

              Krebs cycle = 4 ATP

             

            Total ATP per glucose (under aerobic conditions) = 38    

             ATP

         

             Uses oxygen as final electron acceptor

        

             Completes process by which glucose is converted to

             CO2 and H2O

 

 

Complex I: NADH-CoQ reductase

 

          1.Entry site for NADH + H+

          2.Contains:

              7 Fe-S cluster (non-heme protein)

              flavin mononucleotide phosphate (FMN)

              Coenzyme Q (free in membrane)

         3.Net reaction: NADH + H+ + CoQ ---> NAD+ + CoQH2

         4.ATP produced

 

 

 

 

    

 

 

 

 

Complex II: Succinate-CoQ oxidoreductase

 

          1.Entry site for FADH2

          2.Contains:

             2 Fe-S cluster (non-heme protein)

             Coenzyme Q (free in membrane)

        3.Net reaction: Succinate + CoQ ---> Fumarate + CoQH2

        4.No ATP 

 

     Complex III: CoQH2-cytochrome c oxidoreductase

 

         1.Contains:

             cyctochrome c (free in membrane)

             2 cyctochrome b

             cytochrome c1

             Several Fe-S cluster (non-heme protein)

      2.Net reaction: CoQH2 + 2 cyt c [Fe (III)] ---> CoQ + 2 cyt 

         c [Fe (II)] + 2 H+

      3. ATP produced

 

     Complex IV: Cytochrome oxidase

 

          1.Contains:

             cyctochrome a

             cyctochrome a3

             2 Cu2+

         2.Net reaction: 2 cyt c [Fe (II)] + 1/2 O2 + 2 H+ ---> 2 cyt

            c [Fe (III)] + H2O

         3. ATP produced 

 

 

 

 

 

                                    

 

   Pumping of protons creates higher [H+] on cytosolic side of

   membrane. 

  

   Proton motive force drives synthesis of ATP by ATP  

   synthase. 

                        

   ATP synthase is composed of two subunits. 

 

        Fo proton conducting unit 

        F1 catalytic unit: five polypeptide chains. 

 

       F1 has 3 a and 3 b subunits as well as one g                                    

      subunit.