Question

Description: In order to go from glycolysis to the citric acid cycle we first must harvest pyruvates into acetyl CoA’s. This process involves many small steps which result in the main entrance in the citric acid cycle

Instructions: For this presentation, your goal is to walk the audience through every step that is involved in generating acetyl CoA from Pyruvate. Be sure to focus on any cofactors need and show how this process is reset at the end to allow for another pyruvate molecule to bind.

What to submit: Please record yourself explaining the structures and enzymes of each step of this complex.

Answer 1

Pyruvate that is derived from glucose and other sugars by glycolysis , is oxidised to acetyl-COA and CO2 with the help of pyruvate deydrogenase complex, a cluster of three enzymes .

The PDH complex is a series of multienzyme complex in wich series of chemical intermediates remain bound to the enzyme molecule as substrate is converted to final products.PDH complex contains three enzymes- Pyruvate dehydrogenase (E1), dihydrolipoyl transacetylase(E2) and dihydrolipoyl deydrogenase.(E3) and five coenzymes- Thiamine Pyrophosphate(TPP),FAD,CO-A,NAD and lipoate.

E1 catalyses the first decarboxlation of pyruvate, producing hydroxyethyl-TPP, and then te oxidation of hydroxyethyl group to an acetyl group.The electrons from this oxidation redce the disulfide bond to E2., and acetyl group is transfered into thioester linkage. with one SH group reduced to lipoate.

E2 catalyses the transfer of acetyl group to Coenzyme A, forming acetyl coA.

E3 catalyses the regeneration of disulfide form of lipoate, electrons first pass from FAD to NAD.