Enzyme responsible for the complete oxidation of glucose to CO2 to water is present in
CITRIC ACID CYCLE Synonyms: TCA cycle (tricarboxylic acid cycle), Krebs' cycle, Krebs' citric acid cycle. Points to Remember * It is a cyclic process. * The cycle involves a sequence of compounds interrelated by oxidation-reduction and other reactions which finally produces CO2 and H2O. * It is the final common pathway of break down/catabolism of carbohydrates, fats, and proteins. (Phase III of metabolism). * Acetyl-CoA derived mainly from the oxidation of either glucose or b-oxidation of FA and paly from ceain amino acids combines with oxaloacetic acid (OAA) to form citrate the first reaction of citric acid cycle. In this reaction acetyl-CoA transfers its 'acetyl-group' (2-C) to OAA. * By stepwise dehydrogenations and loss of two molecules of CO2, accompanied by internal re-arrangements, the citric acid is reconveed to OAA, which again stas the cycle by taking up another acetyl group from acetyl-CoA. * A very small catalytic amount of OAA can bring about the complete oxidation of active-acetate. * Enzymes are located in the mitochondrial matrix, either free or attached to the inner surface of the inner mitochondrial membrane, which facilitates the transfer of reducing equivalents to the adjacent enzymes of the respiratory chain. * The whole process is aerobic, requiring O2 as the final oxidant of the reducing equivalents. Absence of O2 (anoxia) or paial deficiency of O2 (hypoxia) causes total or paial inhibition of the cycle. * The H atoms removed in the successive dehydrogenations are accepted by corresponding coenzymes. Reduced coenzymes transfer the reducing equivalents to the electron-transpo system, where oxidative phosphorylation produces ATP moleculesRef: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 336
Cytosol
Mitochondria
Lysosomes
Endoplasmic reticulum
Respiratory chain