Question

Which of the following is essential for conversion of pyruvic acid into acetyl CoA?

• A. lipoic acid
• B. ${\mathrm{NAD}}^{+}$
• C. TPP (Thiamine pyrophosphate)
• D. All of these

Answer 1

The correct option is D All of these

Pyruvate is the end product of glycolysis. Glycolysis is the process of partial oxidation of glucose or similar hexose sugar into 2 molecules of pyruvic acid through a series of reactions releasing some energy (as ATP) and reducing power as NADH (reduced nicotinamide adenine dinucleotide).

Glycolysis occurs in cytoplasm. Krebs cycle occurs in the matrix of mitochondria. Pyruvate enters mitochondria through a specific transport protein pyruvate translocase. It undergoes oxidative decarboxylation to produce ${\mathrm{CO}}_2$ and NADH (reduced nicotinamide adenine dinucleotide).

${\mathrm{NAD}}^{+}$ is reduced to NADH (reduced nicotinamide adenine dinucleotide) during this step. The product combines with sulphur containing coenzyme A to form acetyl CoA or activated acetate. The reaction occurs in the presence of an enzyme complex pyruvate dehydrogenase (made up of a decarboxylase, lipoic acid, TPP, transacetylase and ${\mathrm{Mg}}^{2+}$).