Coenzymes and Vitamins Flashcards Preview

Med Chem > Coenzymes and Vitamins > Flashcards

Flashcards in Coenzymes and Vitamins Deck (27):
1

Cofactors

Assist in the catalytic process, but aren't part of the enzyme itself

2

Apoenzyme

Usually inactive, protein-only (enzyme)

3

Holoenzyme

Apoenzyme + cofactor (active)

4

Types of enzymes that require essential ions

Metal-activated enzymes (require or are stimulated by presence of metal ions- usually K, Ca, Mg)
Metalloenzymes (contain firmly bound metal ions in active sites- usually Zn, Fe, Cu, Co)

5

Two types of coenzymes

Cosubstrates (substrates in reaction and are released from enzyme after reaction)
Prosthetic groups (remain bound to enzyme throughout reaction and must be regenerated to retain enzymatic activity)

6

Obtaining coenzymes

Diet- humans can't make them themselves

7

Water-soluble vitamins

B vitamins, vitamin C, folate

8

Fat-soluble vitamins

Vitamins A, D, E, K

9

Adenosine triphosphate (ATP)

Cosubstrate
Phosphate transfer or energy

10

S-adenosylmethionine (SAM)

Cosubstrate
Transfer of methyl groups

11

Uridine diphosphate glucose

Cosubstrate
Glycosyl group donor

12

Nicotinamide adenine dinucleotide (NAD+) and nicotinamide adenine dinucleotide phosphate (NADP+)

Cosubstrate
Vitamin source: niacin (vitamin B3)
Redox reactions involving 2 electron transfers

13

Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)

Prosthetic group
Vitamin source: riboflavin (vitamin B2)
Redox reactions involving 1 and 2 electron transfers

14

Coenzyme A (CoA)

Cosubstrate
Vitamin source: pantothenate (vitamin B3)
Transfer of acyl groups
Reactive center: -SH group

15

Thiamine pyrophosphate

Prosthetic group
Vitamin source: thiamine (vitamin B1)
Transfer of 2-carbon fragments containing a carbonyl group

16

Pyridoxal phosphate

Prosthetic group
Vitamin source: pyridoxine (vitamin B6)
Transfer of groups to and from amino acids

17

Biotin

Prosthetic group
Carboxyl group transfers and carboxylation

18

Avidin and streptavidin

Proteins with high affinity for biotin

19

Tetrahydrofolate (THF)

Cosubstrate
Vitamin source: folate (vitamin B9)
Transfer of 1-carbon substituents

20

Adenosylcobalamin

Prosthetic group
Vitamin source: cobalamin (vitamin B12)
Intramolecular rearrangements (hydrogen and functional group on adjacent carbon atoms switch places)

21

Methylcobalamin

Prosthetic group
Vitamin source: cobalamin (vitamin B12)
Transfer of methyl groups

22

Lipoamide

Prosthetic group
"Swinging arm" to transfer acyl groups between domains of multi-domain enzyme complexes

23

Retinal

Prosthetic group
Vitamin A
Vision (conjugated pi system: absorption of light)

24

Vitamin K

Prosthetic group
Synthesis of proteins involved in blood coagulation

25

Ubiquinone (Q)

Cosubstrate
Lipid-soluble electron carrier

26

Vitamin D

Hormone that controls Ca+2 intestinal absorption and bone desorption
Formed in skin upon exposure to sunlight (D3 only)

27

Vitamin E

Radical and oxygen scavenger