Question

1. Answer the following questions regarding pryuvate

a.) Which steps in gluconeogensis are used to conver pyruvate to phosphoenolpyruvate?

b.) What can pyruvate not produce in humans

c.) What vitamin is not a co-factor/co-enzyme for pyruvate dehydrogenase complex?

magnesium

ferrous ion

flavin adenine dinucleotide

thiamine pryophosphate

Answer 1

a. During gluconeogenesis, pyruvate carboxylase is the first enzyme in the pathway that synthesizes phosphoenolpyruvate (PEP) from pyruvate. Gluconeogenesis begins in the mitochondria with the formation of oxaloacetate through carboxylation of pyruvate. This reaction also requires one molecule of ATP and is catalyzed by pyruvate carboxylase. This enzyme is stimulated by high levels of acetyl-CoA and inhibited by high levels of ADP. Oxaloacetate is reduced to malate using NADH, a step required for transport out of the mitochondria. Oxaloacetate is decarboxylated and phosphorylated to produce phosphoenolpyruvate by phosphoenolpyruvate carboxykinase. One molecule of GTP is hydrolyzed to GDP during this reaction.

b. Pyruvate cannot be converted into ethanol by alcoholic fermentation that occurs in yeast.

c. Ferrous ions

Pyruvate dehydrogenase complex uses the cofactors thiamine pyrophosphate (TPP), NAD, lipoic acid, and flavin adenine dinucleotide. Ferrous ions are not used by pyruvate dehydrogenase.