Question

Describe how the fumarate produced by the purine nucleotide cycle could be catabolized to CO2.

Answer 1

Purine nucleotide cycle is an important metabolic pathway which helps in production of the fumarate ad ammonia from aspartate and inosine monophosphate. Within this cycle it involves the conversion of the compounds and there are couple of enzymes used including AMP deaminase, adenylosuccinate synthetase and adenylosuccinate lyase. ‘

• During the purine nucleotide cycle, fumarate is converted into malate in presence of the fumarase enzyme.
• This is followed by the conversion of the malate into pyruvate in presence of the decarboxylate malate enzyme. Basically this enzyme helps in catalyzing the conversion of malate and NAD into pyruvate, C02 and NADH. The malate and NAD is used as substrate and it produces pyruvate and NADH and C02 as product.
• The pyruvate further is converted with help of pyruvate dehydrogenase into acetyl CoA and CO2 and the acetyl CoA enters the citric acid cycle which helps in oxidizing the acetyl group into 2 molecules of C02.