THE CITRIC ACID CYCLE

Kadek Rachmawati

The citric acid cycle = Kreb’s cycle = Tricarboxy- lic acid cycle a series of reactions that

oxidized Asetyl-CoA Occur in Mitochondria To yield energy (ATP) TCA cycle the final common pathway for the

aerobic oxidation of carbohydrate, lipid and protein

TCA cycle is common pathway for carbohydrate, lipid and protein

TCA cycle pathway

The function of TCA cycle :

1. Oxidized of Acetyl CoA ATP

( 1 mol Acetyl CoA 12 mol ATP ) 2. The citric acid cycle is AMPHIBOLIC :

- it can oxidized to yield ATP

- it is important in the provision of carbon skeletons for gluconeogenesis, fatty acid synthesis and interconversion of amino acid

Vitamins play key roles of the Citric Acid Cycle

Four of the B vitamins are essential in the citric acid cycle :

1. Ribovlavin FAD

2. Niacin NAD

3. Thiamin TPP

4. Pantothenic acid CoA The B vitamins are essential in energy yielding

metabolism by dehydrogenase enzyme :

- FAD 2 mol ATP

- NAD 3 mol ATP

INHIBITOR OF TCA CYCLEINHIBITOR OF TCA CYCLE

1. Fluoroacetate1. Fluoroacetate• Condensation with CoA Fluoroacetyl-CoACondensation with CoA Fluoroacetyl-CoA• Condensation FluoroacetylCoA with Oxaloace-Condensation FluoroacetylCoA with Oxaloace-

tate tate Fluorocitrate Fluorocitrate inhibit Akoni-inhibit Akoni-

tase enzyme accumulation of citratetase enzyme accumulation of citrate• Fluoroacetate pesticideFluoroacetate pesticide

2. Malonate suksinat dehydrogenase 2. Malonate suksinat dehydrogenase enzymeenzyme

3. Arsenite 3. Arsenite αα-ketoglutarate dehydrogena--ketoglutarate dehydrogena-

se enzymese enzyme

Participation of TCA cycle in fatty Participation of TCA cycle in fatty acid synthesis from glucoseacid synthesis from glucose

Involvement of TCA cycle in Involvement of TCA cycle in transamination and transamination and

gluconeogenesisgluconeogenesis

REGULATION OF TCA CYCLE

REGULATION OF TCA CYCLE

REGULATION OF TCA CYCLE

REGULATION OF TCA CYCLE