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IMS -izzy > Topic 4- enzymes regulation > Flashcards

Topic 4- enzymes regulation Flashcards

1
Q

Serpins

A

> Competitive irreversible inhibitors> protease

>AS > comformational change

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2
Q

List 3 Serine proteases

A

> Trypsin
Chromotrypisin
Elastase

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3
Q

What is Zymogen

A

> inactivated single polypeptide

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4
Q

Describe activation of Chromotrypsin

A

> Zymogen

>Trypsin activates——> chymotrypsin (2 poly)——–> Alpha chymotrypsin (3 poly)

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5
Q

Describe trypsin Activation

A

> Trypsinogen (zymogen)

>Enteropeptidase removes small peptide chains ——-> Trypsin

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6
Q

What does Antithrombin III do?

A

> Controls tight binding of thrombin to serine

>swithches off blood clotting sydtem

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7
Q

Give example of serpins

A

> Serine Proteases

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8
Q

what is the blood clotting cascade

A

> enzyme activation events
Intrinsic/ extrinsic pathways
collects soluble proteins>Fibrin clot formed
amplifies initial sequence

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9
Q

What initiates blood clotting cascade

A

> Blood Factors > serine protease

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10
Q

What happens if there is a deficiency in blood factors ?

A

> Clotting/ bleeding disorders

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11
Q

What factors are involved in enzyme control?

A

> Inhibition
Negative feedback
Phosphorylation
Proteolytic activation

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12
Q

What is endogenous enzyme Inhibition?

A

> Serine protease inhibitors
A1-antitrypsin
Pancreatic Trypsin
Antitthrombin III

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13
Q

A1-antitrypsin

A

> Prevents protease attacking tissue

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14
Q

Pancreatic Trypsin

A

> Regualtes digestive enzyme activity

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15
Q

What is negative feed back

A

> Controls balance
Stop signal when enough is made
Amplify signal> when more needs to be made
pathways > linked

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16
Q

Phosphorylation

A

> Covalent modification
P from ATP transferred to residue via Protein kinase
P removed from residue via protein phosphatase
P indufe charges> change shape > affect activity

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17
Q

Proteolyctic action

A

> Activate zymogen/ pro enzyme
irreversible clevage> amide
bonds

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18
Q

examples of proteolyctic action (2)

A

> Pancrease

>Blood clotting sydtem

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19
Q

What are enzymes?

A

Biological catalysts
specific
protein

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20
Q

How do enzymes work?

A

inc. rate eq reached

lowering AE

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21
Q

How do enzymes lower the AE

A

> Catalytic components
Bind and orientate
Binding and stabalises transitional states

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22
Q

AS properties

A

> Specific 3D shape
small part of protein
Crucial amino acids

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23
Q

What is Michaelis constant

A

> Affinity of enzyme for substrate

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24
Q

Equation for Michaelis constant

A

Km = (K2 + K1)/ K3

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25
Q

What is K1, K2 K3?

A

K1: Rate ES is formed

K2 + K3: Rate ES is dissociated

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26
Q

which is the rate determining constant

A

K3

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27
Q

What is the velocity?

A

Reaction rate

change in product over time

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28
Q

What is IU?

A

International enzyme units

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29
Q

What does IU measure

A

Amount of enzyme that will catalyse 1 micromol of substrate / minute under optimal conditions

30
Q

how many micromoles in a mol

A

10^6

31
Q

What is the vMax?

A

Theoretical max reaction rate

32
Q

What factors affect rate of reaction

A

> [Substrate] and [enzyme]
temperature
pH
Inhibitors

33
Q

How does pH aftect rate

A

proteins protonates and deprotonates

34
Q

What are the types of inhibitors

A

> Reversible - no/ reversible covalent bonds
Irreversible - covalent bonds

> Competitive
Non competitive

35
Q

Describe Competitive inhibitor

A

> binds to AS
Prevents ES
inc [S]> overcome

36
Q

Describe Non competitive inhibitor

A

> Binds to allosteric site> alters shape
EI /EIS
[S] > NO affect

37
Q

What happens to Km and Vmax with a competitve inhibitor

A

Vmax same

Km change

38
Q

What happens to Km and Vmax with a non competitive inhibitor

A

Vmax change

Km same

39
Q

competitive examples

A 
REVERSIBLE
Methotrexate
Ibuprofen
NON REVERSIBLE
Aspirin
40
Q

How do Aspirin and Ibuprofen work?

A

> Inhibit prostaglandis synthesis

>competitively inhibiting COX-1 COX-2

41
Q

How does Methotrexate work

A

> Similar structure to Dihydrofolate> DNA + RNA
Bind to AS
inflammation (low)
cancer (high)

42
Q

Example of non competitive inhibitor

A

> Alanine

43
Q

How does alanine work?

A

> inhibits Pyruvate kinase
-ve feed back
Pyruvate kinase catalyses pyruvate phosphoenol pyruvate to pyruvate which is converted to to alanine

44
Q

What do IC50 values measure?

A

The inhibitor conc that r`educes enzyme activity by 50%

45
Q

What does a low IC50 mean

A

> better inhibitor> less moles needed to inhibit

46
Q

What is an enzyme called with metal in active site?

A

> Metalloprotein

47
Q

Roles of metalloproteins

A

> Redox and oxidation reactions Fe2+/Fe3+

>Regulate enzyme activity

48
Q

Name some major minerals in AS

A

> Mg2+

>Ca2+

49
Q

Name some trace elements

A 
>Cu2+
>Zn2+
>Mn2+
>Mo2+
Fe 2+/3+
50
Q

What are Coenzymes?

A

> Small organic molecules

>Carriers

51
Q

Examples of Coenzymes

A

> Coenzyme A> Acyl units
Biotin and Thiamine Pyrophosphate > C02
NADH / FADH2> carry e-

52
Q

What do NAD+ act as

A

Oxidation agent

accepts H+ and e-

53
Q

How is NAD+ Formed

A

> Niacin sits on larger molecule becomes Nicotinamide

54
Q

Pellagra

A

> Caused by niacin deficiency

55
Q

What does G6DPH stand for?

A

> Glucose-6-phosphate dehydrogenase

56
Q

What is G6DPH needed for?

A

NADPH production

57
Q

Explain conversion of Glucose to Glycolysis in terms of an equation

A

Glucose—->Glucose 6-phosphate——-> 6-phosphoglucono-s-lactone
——–>Glycolysis——->engergy
or
———>Pentose phosphate pathway

58
Q

What does the conversion of Glucose 6-phosphate to 6-phosphoglucono require?
How does the negative feed back work?

A

> Conversion of NADP+ to NADPH
G6PDH

> Inc. NADP > Inc in enzyme activity

59
Q

What happens if G6PDH not present

A

> Primaque haemolytic anaemia and favism

60
Q

What is Primaqye haemolytic anaemia

A

> RBC destroyed faster than made

61
Q

What kind of inherited disease is defective G6PDH

A

> X recessive

62
Q

What 2 products does the pentose pathway poroduce?

A

> Ribose 5- phosphate===> Nucelic Acids

>NADPH====> Reducing power for biosynthesis

63
Q

How does Glutathione repair damaged membrane?
What does it require ?
what relies on this process for production of NADP+

A

> Oxidation and reduction
.>Glutathione reductase, NADPH, Glutathione peroxidase
mitochondria

64
Q

What happens if Glutathione is defective?

A

> Cannot reduce> Run out of glutathione

65
Q

What happens if G6DPH is defiecient

A

> No NADPH production

>Cannot reduce> glutathione runs out

66
Q

What are malaria patients treated with? what does it do?

Affect of deficient G6DPH

A

> Primaquine
Stimulates oxidative species> bad for parasites and mem lipids
defective G6DPH mean mem cannot be repaired> RBC deform

67
Q

What has G6DPH deficiency lead to?

A

> Resistance to malaria

68
Q

What pro drug is used in cancer treatmeant?

A

> 6-mercaptopurine 6-MP

69
Q

How is it activated describe 2 path ways

A

> 3 enzymes metabolise> 6-methyl MP—–>Blocks of DNA sythesis—–>cell death
TPMT metabolises to 6-methyl MP> nothing happens

70
Q

What is TPMT

A

Thiopurine methyl transferase

71
Q

Describe how you can have deficient TPMT

and how this influences your dosage of 6-mercaptopurine 6-MP

A

> 1 chromosome defected> half amount
both chromosome defected> O amount

> Lower dose> Cell lysis pathway more prevalent

IMS -izzy (11 decks)

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