Download Reactions of the TCA Cycle

Common Metabolic pathway for energy Provision from CHO, lipids and
Amino acids (TCA Cycle/ Krebs Cycle)
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Objectives
By the end of the lecture the student should be able to:
Enlist common metabolic pathways of carbohydrate metabolism
Define TCA
Enlist Functions of TCA
Describe different steps of TCA cycle
Discuss its biomedical importance
Definition
TCA cycle, Krebs cycle, citric acid cycle
Cyclic process
Sequence  interMitochondrial matrix, aerobic
2
H2O
Functions of TCA
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Provides energy
Major pathway to oxidize acetyl Co-A formed from the oxidation of
– Glucose
– Amino acids
– Fatty acids
Provides substrates for
– Gluconeogenesis
– Heme
– Non-essential amino acids
– Fatty acids
Key Co-Enzymes
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Niacin
– NAD
Riboflavin
– FAD
Thiamine
– TPP
– Coenzyme A
– CoA
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Reactions of the TCA Cycle
Oxidative decarboxylation of Pyruvate
Synthesis of citrate from acetyl CoA and Oxaloacetate
Isomerization of Citrate
Oxidation and decarboxylation of isocitrate
Oxidative decarboxylation of α- ketoglutarate
Cleavage of Succinyl CoA
Oxidation of succinate
Hydration of fumerate
Oxidation of malate
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Biomedical Importance
Final common pathway  CHO, proteins fats through formation of 2 C
unit acetyl CoA
Catabolic role-> acetyl CoA ->oxidized ->CO2 , H2O-> energy
Intermediate-> heme, non-essential aa, FA synthesis, cholesterol and
steroid synthesis
References
Lippincott’s biochemistry 5 ed. page 109
Harper’s Biochemistry
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