Pyruvate Dehydrogenase Complex

Question 1

Oxidative decarboxylation: pyruvate dehydrogenase (PDC) oxdizes (or removes H) __1__, __2__ is given off, and __3__ is reduced.

Answer 1

1. pyruvate
2. CO2
3. NAD+ (reduced into NADH)

Question 2

Once PDC oxidizes pyruvate, it is now an activated _____ unit

Answer 2

acetyl

this means it’s attached to CoA

Question 3

once pyruvate is oxidized by PDC, what is the final product called

Answer 3

acetyl-CoA

Question 4

Why is oxidative decarboxylation by PDC so tightly regulated?

Answer 4

because this step is irreversible

Question 5

How is PDC regulated?

Answer 5

via allosteric regulation, by both allosteric inhibitors and allosteric activators. Increase in substrates used during the rxn would be activators and increase products, and an increase in products would be inhibitors.

Question 6

Name some allosteric activators of PDC

Answer 6

pyruvate, AMP, CoA, NAD+, Ca2+

Question 7

Name some allosteric inhibitors of PDC

Answer 7

acetyl-CoA, NADH, ATP, fatty acids

Question 8

Many enzymes need cofactors (nonprotein compounds) for their biological activity. If the cofactor is very tightly or covalently bonded to the enzyme, it is referred to as a ____ group

Answer 8

prosthetic

Question 9

What is a cofactor needed for the activity of PDC in oxidative decarboxylation

Answer 9

vitamin B1 (thiamine pyrophosphate, TPP)