Lecture 12: intro to CoE

Question 1

coenzymes are often bound to _____ to assist in catalysis

Answer 1

enzymes

Question 2

a coenzyme (is/ is not) protein in nature

Answer 2

is not

Question 3

prosthetic groups are a ___ of enzymes and are typically (tightly/ loosely) bound, sometimes covalent

Answer 3

subset; tightly bound

Question 4

TPP facilitates _____ and ____ reactions

Answer 4

activation/ transfer of aldehydes and decarboxylation

Question 5

FAD, FMN and NAD(P) facilitates a ____ reaction because they are ____

Answer 5

oxidation/ reduction; good at transferring electrons

Question 6

CoEA facilitates a _____ reaction

Answer 6

acyl group activation/ transfer [as a carrier]

Question 7

lipoamide facilitates a _____ reaction

Answer 7

acyl group activation/ transfer; redox reaction

Question 8

niacin (NAD+/NADH) functions in a ____ reaction and (is/ not) a prosthetic group

Answer 8

redox reaction; is not a prosthetic group

Question 9

FAD/ FADH2 functions in a ____ reaction and (is/ not) a prosthetic group

Answer 9

redox reaction; is a prosthetic group

Question 10

lipoamide is from ____ and functions how?

Answer 10

lipoic acid; its disulfide bond is readily reduced and able to function as a temporary carrier of an acyl group

Question 11

lipoamide (is/ not) a prosthetic group

Answer 11

is a prosthetic group

Question 12

PDH plays an important role in ____ and ____; it mediates the reaction of 2-pyruvate (C3) to ____

Answer 12

glycolysis and TCA cycle; acetyl-CoA and CO2

Question 13

acetyl-CoA is oxidized to ____ in TCA cycles; generates many molecules of ATP via _____

Answer 13

CO2; oxidative phosphorylation

Question 14

TPP, LA and FAD (are/ are not) prosthetic groups

Answer 14

are prosthetic groups

Question 15

swinging arm of lipoamide: step 1; via E(1/2) and ___

Answer 15

pyruvate decarboxylation [CO2 has to leave] via E1 and TPP

Question 16

swinging arm of lipoamide: step 2; via E(1/2) and ___+____

Answer 16

reduction and transacetylation [disulfide bond of a lipoamide bond is reduced to carry the 2C group] via E1/E2 and TPP+lipoamide

Question 17

swinging arm of lipoamide: step 3; via E(1/2) and ____

Answer 17

minor step; repositioning of the acetyl group [2C group has to move from one arm to the other] via E2 and LA

Question 18

swinging arm of lipoamide: step 4; via E(1/2), and ___+____

Answer 18

transthiolation and formation of acetyl CoE-A [product is formed; need to reset the PDH complex] via E2, LA+CoA-SH

Question 19

swinging arm of lipoamide: step 5; via E(1/2/3) and ___+___

Answer 19

re-oxidization of lipoamide [reset the enzyme] via E2/E3, FAD+LA

Question 20

TPP in decarboxylation of pyruvate has a ____ carbon

Answer 20

acidic carbon [carbanion]

Question 21

decarboxylation in the 1st step produces ____

Answer 21

resonance-stabilized carbanion [HETTP]

Question 22

negative charge on C of HETTP makes it (more/ less) reactive, making it bind to ____

Answer 22

more reactive; will bind to lipoamide arm

Question 23

when you hydrolyze a group of ATP it releases ____

Answer 23

energy

Question 24

function of FAD in reaction

Answer 24

reforms disulfide bond on lipoamide arm by redox reaction

Question 25

function of NAD+ in reaction

Answer 25

oxidizes FADH2 back to FAD

Question 26

NADH (is/ not) a prosthetic group

Answer 26

is not

Question 27

swinging arm of lipoamide: step 6; via E(1/2/3) and ___+____

Answer 27

re-oxidation of FAD [NAD+ oxidizes FADH2 back to FAD] via E3 and FAD+NAD