Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry > Regulation of enzyme activity > Flashcards

Regulation of enzyme activity Flashcards

1
Q

5 says of regulating enzymatic activity

A

Allosteric control
Multiple forms of enzymes
Reversible covalent modification
Proteolytic activation
Controlling the amount of enzyme present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Example of reversible covalent modification

A

Phosphorylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does allosteric regulation do?

A

Modulates activity of key enzymes through reversible binding ina different site than active site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Is allosteric regulation fast or slow working?

A

Fast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are allosteric effectors typically?

A

Small chemicals either positive or negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Example of allosteric enzyme

A

Aspartate transcarbamoylase (ATCase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does Aspartate transcarbamoylase (ATCase) catalyse?

A

First reaction of pyrimidine synythessi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the committed step?

A

The step which is determines what reactive pathway you’ll take, after that step (typically the first step) there can be no more control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is feedback inhibition

A

When the last product inhibits the first step so the reaction can’t happen again
Like negative feedback

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Is cytidine a pyrimidine or purine?

A

Pyrimidine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What kind of kinetics does ATCase display?

A

Sigmoidal kinetics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How many subunits does native ATCase consist of?

A

12:
6 regulatory (3 dimers)
6 catalytic (2 trimers)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is an analog?

A

Something that is structurally and chemically similar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does PALA do?

A

Freeze it in the R state (suicide inhibitor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Is ATP a positive or negative regulator?

A

Postive (favours R-state)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Is ATP a positive or negative regulator?

A

Negative (favours T-state)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Is ATP purine or pyrimidine?

A

Purine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do ATP block CTP ?

A

Because there has to be equal amounts of purine and pyrimidine so the excess amount of CTP will not act because of the limiting number of ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What can the concerted model be described as?

A

All or nothing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where does CTP bind?

A

Regulatory site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What kind of cooperatively does haemoglobin use?

A

Sequential cooperatively

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which amino acids are most commonly phosphorylated?

A

Tyrine
Serine
Threonine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What can ATP serve as a donor of?

A

Phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What does kinases need to phosphorylate and gives it high specificity?

A

Consensus sequences which serves as a marker for which amino acid to phosphorylate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Are the consensus sequences the same for all kinases?

A

No they are very different

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

6 reasons for phosphorylation being highly effective

A

Free energy
Adds 2 negative charges to protein
Can form 3 or more hydrogen bonds
Is fast
Often evoke highly amplified effects
ATP is cellular energy currency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does training do to the phosphorylation of many proteins?

A

Increases it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Types of proteolysis (a common way of activating enzymes)

A

Digestive enzymes
Blood clotting
Apoptosis
Hormones
Collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does elastase cleave?

A

Proteins in bacteria, therefor important in lungs to protect them from infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

2 fast reacting enzyme regulation mehtods

A

Allosteric control
Reversible covalent modification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What does allosterism describe?

A

The change in the affinity for binding of a ligand or substrate that is caused by the binding of another ligand away from the active site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What happens to enzymatic catalysis if the allosteric effector is negative?

A

The enzymatic catalysis is reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What inhibits aspartate transcarbomylase?

A

The end product of the pathway
Feedback inhibition

34
Q

What does the fact that ATCase display sigmoidal kinetics indicate??

A

Cooperativity

35
Q

What kind of regulator is ATP?

A

Positive

36
Q

What kind of regulator is CTP?

A

Negative

37
Q

Which state does ATP favour?

A

R-state

38
Q

Which state does CTP favour?

A

T-state

39
Q

What are allosteric interactions in ATCase mediated by?

A

Large changes in quaternary structure

40
Q

What is the allosteric coefficient?

A

The ratio of enzyme in the T state to that in the R state

41
Q

Which mechanism of allosteric enzymes does ATCase adhere to? Concerted or sequential?

A

Concerted

42
Q

What is L?

A

The equilibrium constant for the T-toR equilibrium

43
Q

What alters the value of L?

A

Allosteric effectors (heterotrophic effectors)

44
Q

What effect does ATP have on Km?

A

Lowers it

45
Q

What effect does ATP have on affinity?

A

Highers it

46
Q

What effect does CTP have on affinity?

A

Lowers it

47
Q

What effect does CTP have on Km?

A

Highers it

48
Q

Which is faster, the concerted model or the sequential?

A

Concerted

49
Q

3 most common target residues for phosphorylation

A

Tyrosine
Serine
Threonine

50
Q

What controls the extent of protein phosphorylation?

A

Kinases and phosphatases

51
Q

How does protein kinases modify proteins?

A

By attaching a phosphate to a serene, throning or tyrosine

52
Q

What do protein phosphates do?

A

They remove phosphates added by kinases

53
Q

What does phosphorylation in glycogen phosphorylase cause?

A

A conformation change

54
Q

What activates protein kinase A?

A

Protein kinase A

55
Q

How does protein kinase A activate cyclic AMP?

A

It alters the quaternary structure

56
Q

What causes protein kinase A to dissociates from the catalytic subunits?

A

cAMP binding to PKA’s regulatory (R) subunits

57
Q

What is Cushing’s syndrome?

A

A collection of diseases

58
Q

What does Cushing’s syndrom result from?

A

Excess secretion of cortisol by adrenal cortex

59
Q

What does unregulated excretion of cortisol cause?

A

Suppression of the immune system
Inhibition of bone growth

60
Q

What is zymogen?

A

The inactive precursor that is cleaved to form an active protease enzyme

61
Q

What is proprotein or proenzyme?

A

Precursors that are cleaved to form other proteins

62
Q

What are the 3 chains in chymotryosing linked together by?

A

Covalently linked by disulphide bridges

63
Q

How much of the pancreas is acing cells?

A

82%

64
Q

Which cells in the pancreas produce hormones?

A

Endocrine cell

65
Q

What does acing cells do?

A

Store and secrete digestive enzymes

66
Q

Which digestive enzymes are secreted by the pancreas?

A

Amylase
Protease
Lipase
HCO3-

67
Q

What are many digestive enzymes stored as?

A

Inactive zymogens or proenzymes in secretory vesicles in the pancreas

68
Q

When are zymogens secreted?

A

Following a meal

69
Q

Where are zymogens secreted?

A

Pancreatic juice

70
Q

Where ar zymogens activated?

A

In the gastrointestinal tract

71
Q

What converts trypsinogen to active trypsin?

A

Enteropeptidase

72
Q

What does trypsin activate?

A

All the pancreatic zymogens

73
Q

What does pancreatic trypsin inhibitor protect against?

A

Premature activation of trypsin in the pancreas

74
Q

How does trypsin inhibitor work?

A

It binds so tightly to the active site that it cannot progress to the transition state

75
Q

What are neutrophil elastase secreted by?

A

Neutrophils

76
Q

When are neutrophil elastase secreted?

A

During inflammation

77
Q

What is elastase?

A

A serine protease

78
Q

What produces elastase?

A

Pancreas

79
Q

What can lack of enzyme inhibitors lead to?

A

Damage of connective tissue and more enzyme specific places (like pancreas or alveolar wall)

80
Q

What is methionine 358 essentail for binding?

A

Elastase

Biochemistry (28 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions