Question

. Explain how AceylCoA is exported out of the mitochondrial matrix into the cytoplasm. You must regenerate any used TCA intermediates. Names of intermediates and enzymes will suffice.

Answer 1

ans:-) The citric acid cycle utilizes mitochondrial enzymes. The first step is fusion of the acetyl group of acetyl-CoA with oxaloacetate, catalyzed by citrate synthase. and they easily come in the mitochindrial matrix into the plasma.

so many intermediates and enzyme are used to complete the TCA cycle:

CoA-SH and heat are released and citrate is produced. Citrate is isomerized by dehydration and rehydration to isocitrate. The enzyme aconitase catalyzes these two steps using cis-aconitate as the intermediate. The next two steps are catalyzed by isocitrate dehydrogenase. Dehydrogenation of isocitrate forms oxalosuccinate which decarboxylates to alpha-ketoglutarate. Alpha-ketoglutarate is further oxidatively decarboxylated by alpha-ketoglutarate dehydrogenase—a multienzyme complex. Succinyl-CoA is formed in this unidirectional reaction.

Succinate thiokinase converts succinyl-CoA to succinate, while first generating ATP/GTP by substrate-level phosphorylation. Succinate is acted upon by succinate dehydrogenase, requiring FAD and Fe-S proteins to form fumarate. Fumarase adds water to a double bond of fumarate yielding malate. Malate regenerates oxaloacetate by action of NAD+-dependent malate dehydrogenase, completing the cycle.