Fates of Pyruvate

Question 1

Alternate fates of pyruvate

Answer 1

Oxidative decarboxylation
Carboxylation of pyruvate to oxaloacetate
Reduction of pyruvate to ethanol

Question 2

Oxidative decarboxylation of pyruvate via enzyme?

Pyruvate -> Acetyl coa

Irreversible

Major fuel in TCA and fatty acid synthesis (source of acetyl coa for TCA and FA synthesis)

Irreversible

Located in mitochondria

Answer 2

Pyruvate dehydrogenase

Question 3

Cofactors and coenzymes used in decarboxylation of pyruvate

Answer 3

Thiamine pyrophosphate (TPP) B1 
Lipoic acid
Coenzyme A from B5 
FAD from B2
NAD from Niacin B3

Question 4

Pyruvate dehydrogenase

Oxidative decarboxylation of pyruvate -> acetyl coa is inhibited by

Answer 4

Acetyl CoA

Question 5

Inhibits pyruvate dehydrogenase
Leads to accumulation of pyruvate

Common in alcoholics: pyruvic and lactic acidosis

Answer 5

Thiamine deficiency

Question 6

Inherited pyruvate dehydrogenase deficiency

Inc pyruvic and lactic acid

Answer 6

Alper’s syndrome

Question 7

Conversion of pyruvate -> oxaloacetate by enzyme

Replenishes TCA cycle intermediates and provides substrate for GLUCONEOGENESIS

Carboxylation of pyruvate to oxaloacetate

Irreversible

Located in mitochondria

Synthetic group?

Activated by?

Answer 7

Pyruvate carboxylase

Biotin

Acetyl coa

Question 8

Carboxylation of pyruvate to oxaloacetate is dependent on

Answer 8

Biotin B7

Question 9

Decarboxylation of pyruvate via pyruvate decarboxylase in yeast and microorganisms

Another reaction similar to pyruvate dehydrogenase

Requires this cofactor

Answer 9

Thiamine pyrophosphate

Reduction of pyruvate to ethanol

Question 10

Occurs in yeast and some bacteria (intestinal flora)

Thiamine pyrophosophate-dependent pathway via
Acetaldehyde dehydrogenase

Located in cytosol

Answer 10

Ethanol synthesis from pyruvate

Question 11

Those that form intermediates of a metabolic pathway

“Filling up reactions”

ex. TCA

Answer 11

Anaplerotic reactions

Filling up reactions

Question 12

Anaplerotic reactions

Answer 12

Carboxylation of pyruvate -> oxaloacetate by pyruvate carboxylase

Hydration of glutamate to a-ketoglutarate by glutamate dehydrogenase

Transamination of aspartate to oxaloacetate by aspartate aminotransferase (allows incorporation of acetyl coa into citrate via citrate synthase in glyoxysomes)