Mne Lect 05 - Pyruvate Dehydrogenase And The Tca Cycle

Front 1

Structure of Coenzyme A

Back 1

-adenylate nucleotide
-pantothenic acid
-b-mercaptoethylamine
***note reactive thiol group, which forms a thioester with acetate in acetyl-coA

Front 2

What are the five coenzymes of the pyruvate dehydrogenase complex? What are the vitamin precursors for all of them?? How many enzymes in the complex total?

Back 2

1. TPP (thiamine phosphate) – thiamine 
2. FAD (flavin adenine dinucleotide) – riboflavin
3. CoA-SH (coenzyme A) – pantothenic acid
4. NAD+ - nicacin 
5. lipoic acid – no vitamin precursor, our bodies make this. Found as nutritional supplement in stores.

3 enzymes total!

Front 3

3 enzymes of the pyruvate dehydrogenase complex and what happens in each!

Back 3

E1: Pyruvate dehydrogenase
E2: Dihydrolipoyl transacetylase
E3: Dihydrolipoyl dehydrogenase

A. E1:
1. TPP reacts with pyruvate, which undergoes decarboxylation. The acetyl portion becomes a hydroxylethyl derivative covalently attached to TPP
2. Pyruvate dehydrogenase then transfers two electrons and the acetyl group to lipoic acid. This reduces the oxidized lipoic acid and transfers the acetyl group to the lipoyllysl group to form an acetyl thioester

B.E2
3. Transfer of the acetyl group to CoA-H, forming acetyl-CoA

C. E3
4. Reoxidizes lipoicacid, transferring reducing equivalents to NAD+

Front 4

Lipoic acid can be in what three stages? what order do these all come in?

Back 4

3 stages (in order):
1. Oxidized
2. Acetylated form
3. Reduced form

Front 5

TPP --

Back 5

(thiamine phosphate)

Hint 5

thiamine

Front 6

lipoic acid – .

Back 6

no vitamin precursor, our bodies make this. Found as nutritional supplement in stores

Front 7

NAD+ --

Back 7

nicacin

Front 8

CoA-SH --

Back 8

(coenzyme A)

Hint 8

pantothenic acid

Front 9

FAD –

Back 9

(flavin adenine dinucleotide)

Hint 9

riboflavin