Lecture 12: intro to CoE Flashcards
coenzymes are often bound to _____ to assist in catalysis
enzymes
a coenzyme (is/ is not) protein in nature
is not
prosthetic groups are a ___ of enzymes and are typically (tightly/ loosely) bound, sometimes covalent
subset; tightly bound
TPP facilitates _____ and ____ reactions
activation/ transfer of aldehydes and decarboxylation
FAD, FMN and NAD(P) facilitates a ____ reaction because they are ____
oxidation/ reduction; good at transferring electrons
CoEA facilitates a _____ reaction
acyl group activation/ transfer [as a carrier]
lipoamide facilitates a _____ reaction
acyl group activation/ transfer; redox reaction
niacin (NAD+/NADH) functions in a ____ reaction and (is/ not) a prosthetic group
redox reaction; is not a prosthetic group
FAD/ FADH2 functions in a ____ reaction and (is/ not) a prosthetic group
redox reaction; is a prosthetic group
lipoamide is from ____ and functions how?
lipoic acid; its disulfide bond is readily reduced and able to function as a temporary carrier of an acyl group
lipoamide (is/ not) a prosthetic group
is a prosthetic group
PDH plays an important role in ____ and ____; it mediates the reaction of 2-pyruvate (C3) to ____
glycolysis and TCA cycle; acetyl-CoA and CO2
acetyl-CoA is oxidized to ____ in TCA cycles; generates many molecules of ATP via _____
CO2; oxidative phosphorylation
TPP, LA and FAD (are/ are not) prosthetic groups
are prosthetic groups
swinging arm of lipoamide: step 1; via E(1/2) and ___
pyruvate decarboxylation [CO2 has to leave] via E1 and TPP
swinging arm of lipoamide: step 2; via E(1/2) and ___+____
reduction and transacetylation [disulfide bond of a lipoamide bond is reduced to carry the 2C group] via E1/E2 and TPP+lipoamide
swinging arm of lipoamide: step 3; via E(1/2) and ____
minor step; repositioning of the acetyl group [2C group has to move from one arm to the other] via E2 and LA
swinging arm of lipoamide: step 4; via E(1/2), and ___+____
transthiolation and formation of acetyl CoE-A [product is formed; need to reset the PDH complex] via E2, LA+CoA-SH
swinging arm of lipoamide: step 5; via E(1/2/3) and ___+___
re-oxidization of lipoamide [reset the enzyme] via E2/E3, FAD+LA
TPP in decarboxylation of pyruvate has a ____ carbon
acidic carbon [carbanion]
decarboxylation in the 1st step produces ____
resonance-stabilized carbanion [HETTP]
negative charge on C of HETTP makes it (more/ less) reactive, making it bind to ____
more reactive; will bind to lipoamide arm
when you hydrolyze a group of ATP it releases ____
energy
function of FAD in reaction
reforms disulfide bond on lipoamide arm by redox reaction