Biochemistry Exam I Lecture 5

Front 1

the activity of an enzyme is dependent up the integrity of its ____

Back 1

fold

Front 2

what is a common way to reducing the amount of active enzyme

Back 2

focusing on the integrity of its fold

Front 3

how do you overcome a covalent modification of an enzyme

Back 3

de novo synthesis

Front 4

how can proteolysis activate an enzyme?

Back 4

enzyme might be "pro enzyme" which has an extra domain that keeps it inactive and when you remove it the protein actually becomes active

Front 5

where can you covalently add small molecules that change the function of an enzyme

Back 5

commonly on the R group

Front 6

______ is a well characterized common covalent modification that can be rapidly reversed

Back 6

phosphorylation

Front 7

what are some other common covalent modifications of enzymes

Back 7

phosphorylation
N glycosylation
O glycosylation
Hydroxylation
Carboxylation

Front 8

what R group is commonly modified by phosphorylation?

Back 8

resideus with hydroxyl
ser thr tyr

Front 9

what R group is commonly modified by N glycosylation

Back 9

Asn
RNHsugar

Front 10

what R group is commonly modified by O glycosylation

Back 10

RO sugar
ser thr

Front 11

what R group is commonly modified by hydroxylation

Back 11

hydroxl group added to R group
Pro lys

Front 12

what R group is commonly modified by carboxylation

Back 12

COOH added to R group
glu

Front 13

_____ _____ is a common cellular strategy to regulate biosynthetic pathways

Back 13

feedback inhibition

Front 14

a _____ site is a site that is physically separated from the active site but that when occupied by a ligand, alters the catalytic ctivity of the enzyme

Back 14

allosteric

Front 15

do allosteric inhibitors follow MM?

Back 15

no!

Front 16

_______ enzymes are almost always comprised of more than one subuit, and complex interactions occur between these subunits that allow events occurring on one subunit to be communicated to another subunit

Back 16

allosteric

Front 17

what is the shape of an allosteric enzyme graph

Back 17

sigmoid S

Front 18

explain T and R states

Back 18

T is tense and substrate binding is very poor and relaxed is when substrate binds well and is enzymatically active

Front 19

an allosteric inhibitor tends to stabilize the __ state thus making the sigmoid curve more extreme

Back 19

T

Front 20

when might allosteric regulation look more like MM curve

Back 20

allosteric activators

Front 21

what is our important model of allosteric regulation

Back 21

CTP or cytidine triphosphate

Front 22

Describe the pathway to CTP

Back 22

aspartate + carbamoyl phsophate --> using ATCASE and several reactions + 2ATP make CTP

Front 23

ATCase is made up of how many subunits

Back 23

12
6 are catalytic
6 are regulatory

Front 24

Binding of the first aspartate of a ATCase is difficult because

Back 24

it can only bind to the T state

Front 25

____ will be an allosteric inhibitor of ATCAase

Back 25

CTP

Front 26

Binding of CTP to ATCase stabilizes which state of the enzyme

Back 26

T

Front 27

will adding more CTP increase or decrease K.5

Back 27

increase! this means it actually slows it down (less affinity)

Front 28

In the case of the CTP allosteric pathway, what does adding ATP do

Back 28

ATP acts as an activator-- decreases K.5

Front 29

_____ are two or more forms of an enzyme that catalyze a given reaction in cells

Back 29

isoenzymes

Front 30

what is an example of an isoenzyme

Back 30

LDH

Front 31

what are the two isoenzyme forms of LDH

Back 31

M and H

Front 32

What are the possible combos of LDH

Back 32

M4, M3H, M2H2, M1H3, H4

Front 33

explain the two difference from H4 and M4 in LDH

Back 33

H4 has higher affinity for substrates and is allosterically inhibited by pyruvate

Front 34

where do you find more H subunits of LDH? M subunits?

Back 34

H in heart
M in skeletal muscle and liver