Biological oxidation

1. Biological oxidation

2. Oxidation &Reduction
 Oxidation:addition of O2 or removal of H 2
nortcele/
e.g. Cu+becomes Cu++ and electron
 Reduction:addition of H 2
O fo lavomer ro nortcele/
2
e.g. Cu++ and electron becomes Cu+
REDOX reactions happens together and usually associated by energy
liberation necessary for the cell.

3. Respiratory chain
 Definition:series of carriers which electrons transferred from lower REDOX
potential (lower e- affinity) to higher REDOX potential (higher è affinity) till reach
oxygen to form oxygen (oxidation) with liberation of energy ,part of it stored by
production of ATP from ADP+Pi (phosphorylation) ,so this process called
oxidative phosphorylation and occurs in the inner mitochondrial membrane
 The other part of energy released in the form of heat ,but if direct transport of
H2 to O 2
gnivil egamad taht taeh fo mrof eht ni etarebil lliw ygrene evissam,
)noitarutaned( snietorp sti gnigamad yb sllec
.
 All the substrates join the respiratory chain through NADH+(H+) and gives 3ATP
,while FADH2 gives 2ATP

4. Components of respiratory chain
 NADflavoproteincoenzymes QcytochromesO 2
 and 5 separated complexes 1
&
23
&
4
&
5
 5complex is called ATP synthase which catalyzes ATP synthesis

5.  Oxidative phosphorylation (coupling mechanism)
ADP+PiATP (PHOSPHORYLATION)
By using energy liberated during transfer of electrons through the components of the respiratory chain
(oxidation).
 Inhibitors of the the respiratory chain
They inhibit oxidation so in turn inhibit ATP from ADP+Pi noitalyrohpsohp oN(
)
Example:cyanides and carbon monoxide inhibit it .
 Uncouplers of oxidative phosphorylation
Allow oxidation ,but prevent phosphorylation of ADP ,so there will be energy but won’t be ATP energy will
be lost as heat which explain the sensation of hotness following ingestion of these substances
Examples:
1. Thyroxine
2. Progesterone (Released during menstrual cycle during ovulation)
3. Ca injection and high doses of salcylates
4. Chloropromazine
5. Arsenic compounds
6. Uncoupler proteins "UCP" 1
_
5