Page 50 - Biochemistry2 (08PB403)

II. Biologic Oxidation & ATP Synthesis

• When a mixture of hydrogen (H2) and oxygen (O2) is allowed to
ignite, a combustion reaction proceeds with the liberation of heat
energy and water (H2O):

Combustion

• H2 + 1/2 O2 ----------- H2O + Energy

• This situation is similar to the major reactions of biologic
oxidation.

• In biologic oxidation, however hydrogen is not present in the free
state, but linked to coenzymes in the form of NADH + H+ and
FADH2.

• Hydrogen atoms act as electron donors to electron transport chain
(ETC), and protons are driven to the outer surface of inner
mitochondrial membrane, thus creating a proton gradient.

• The proton gradient energy is used to build up ATP by ATP

synthase (in complex V). ATP formation in this way is called

oxidative phosphorylation. 50