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Biochemistry > enzyme regulation > Flashcards

enzyme regulation Flashcards

1
Q

substrate-level control acts on

A

a single reaction

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2
Q

feedback control targets

A

a different step in the pathway

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3
Q

activator ______ more products

A

promote

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4
Q

inhibitors _____ more products

A

prevent

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5
Q

strategies for enzyme regulation:

regulate the amount or availability (on/off switch)

A

temporal control of gene expression

protein degradation

enzyme compartmentalization

substrate availability

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6
Q

strategies for enzyme regulation:

regulate the activity of the enzyme (volume control)

A

isozymes and isoforms

covalent modifications

allostery

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7
Q

regulation of enzyme amount:

temporal control of gene expression (controlling gene expression of enzyme of interest)

A

regulation of chromatin remodeling

regulation of transcription

regulation of splicing and processing

regulation of transport out of nucleus

degradation of mRNA in cytosol

translational regulation

protein modifications

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8
Q

regulation of enzyme amount:

protein/enyzme degradation

A

intracellular digestion in lysosomes (low pH and acid hydrolases degrade in lysosome)

proteasome

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9
Q

regulation of availability:

enzyme compartmentalization

A

enzymes only acting in a specific location

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10
Q

regulation of availability:

substrate availability

A

availability of 2nd messengers in signaling cascades

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11
Q

regulation of enzyme activity:

isozymes and isoforms function to

A

catalyze the same reaction but with different efficiencies by mixing matching subunits: paralogs (gene duplication) and alternative splicing

also due to heterozygous alleles, monomer vs dimer/trimer etc, covalent modifications

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12
Q

lactate dehydrogenase (LDH) participates in

A

lactic acid fermentation pathway

pyruvate (end product from glycolysis) + NAHD + H+ –> NAD+ + lactic acid

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13
Q

LDH is a

A

tetramer (4 available isoform units)

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14
Q

LDH 1 > 2

A

heart attack

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15
Q

LDH 5 > 4

A

liver damage

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16
Q

regulation of enzyme activity:

reversible covalent modifications

A

creates nonproteinogenic amino acids by adding 1 or more functional groups to activate/inactivate the enzyme

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17
Q

reversible covalent modification:

lipids

A

myristoylation

farnesylation (farnesyl is an intermediate in cholesterol synthesis)

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18
Q

reversible covalent modification:

nucleic acids

A

ADP ribosylation

19
Q

reversible covalent modification:

proteins

A

ubiquitination

20
Q

reversible covalent modification:

carbohydrates

A

greatest source of diversity to the proteome

21
Q

how are carbohydrates linked

A

O- or N- linkages

22
Q

reversible covalent modification:

small molecules- gamma-carboxylation

A

gamma-carboxylation

carbon linkage

23
Q

reversible covalent modification:

small molecules - sulfation

A

sulfation (oxygen linkages)

24
Q

reversible covalent modification:

small molecules - acetylation and methylation

A

acetylation and methylation

used a lot in histone modifications

25
Q

methyl groups can go on either

A

arinine and lysine (nitrogen linkages)

26
Q

acetyl groups can go on

A

lysine (nitrogen linkages(

27
Q

reversible covalent modification:

small molecules - phosphorylation

A

oxygen linkages

28
Q

why is phosphorylation activating?

thermodynamics:

kinetics:

cell processes:

shape and charge complementarity:

A

thermodynamics: ATP hydrolysis (putting phosphate on) can drive unfavorable reactions- negative deltaG)
kinetics: physiological processes dictate reaction rate

cell processes: ATP amounts dictated by metabolism (energy charge); signal transduction amplification (catalytic turnover)

shape and charge complementarity: each phosphate adds (-2) charge and has potential to make 3 H-bonds

29
Q

kinases

A

adds phosphates

30
Q

phosphatases

A

remove phosphates

31
Q

the name of a kinase indicates

A

on which amino acid the phosphate will be added onto

e.g. serine kinases phosphorylate serine residues/amino acids

32
Q

regulation of enzyme activity:

irreversible covalent modifications

A

proteolytic activation

33
Q

zymogen

A

enzymes that need to be cleaved to become active

34
Q

examples of zymogens

A

proteases (digestive enzymes, collagenase, and caspases)

collagen

blood clotting factors

insulin/hormones

35
Q

regulation of enzyme activity:

allostery:

heteroallostery:

homoallostery:

A

heteroallostery: effector binds at the allosteric site
homoallostery: cooperativity

36
Q

example of allostery

A

ATCase in nucleotide metabolism

37
Q

binding of CTP perfers the

A

T/inactive state

inhibition of ATCase

38
Q

binding of ATP prefers the

A

R/active state

activation of ATCase

39
Q

LDH 1 =

40
Q

LDH 2 =

41
Q

LDH 3 =

42
Q

LDH 4 =

43
Q

LDH 5 =

Biochemistry (32 decks)

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