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Alia - Biology > Lecture 10-Enzymes > Flashcards

Lecture 10-Enzymes Flashcards

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1
Q

What are enzymes?

A

Large,globular protein molecules

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2
Q

What do enzymes display?

A

Specificity

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3
Q

List all the enzyme functions?

A 
Digestion
DNA synthesis
Cell signalling
Respiration
Metabolism
Cell movement + growth
Cellular digestion
Immunology
Transport of CO2
Control of vascular tone
Control of neuronal pathways
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4
Q

What are the enzymes in the stomach?

A

HCL + pepsin

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5
Q

What are the enzymes in the pancreas?

A

Pancreatic amylase + lipase

Trypsin

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6
Q

Small intestine enzymes?

A

Lactase
Maltase
Sucrase-isomaltase
Peptidase

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7
Q

What enzymes can breakdown carbs?

A

Amylase
Sucrase-isomaltase
Maltase
Lactase

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8
Q

What enzymes can breakdown proteins?

A

Pepsin
Trypsin
Peptidase

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9
Q

Active site?

A

The region of an enzyme where the substrate molecule bind + undergo a chemical reaction

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10
Q

Where does catalytic power come from?

A

The binding of substrates together in an orientation that promotes the formation of TRANSITION STATES

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11
Q

What is activation energy?

A

A measure of the energy needed for the conversion of the substrate to the reactive state

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12
Q

What is the transition state

A

The highest potential E along the reaction coordinate . The POINT OF NO RETURN = where reactant molecules go on to form products

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13
Q

Describe a typical reaction?

A

Upon substrate binding = enzyme stretch/distort a KEY BOND + WEAKEN it ,so less activation energy needed to break the bond at the start of the reaction

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14
Q

What do proteolytic enzymes do?

A

Break down proteins

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15
Q

What bonds do Trypsin break?

A

Lysine + arginine residues

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16
Q

What does Thrombin do?

A

Catalyse the hydrolysis of Arg-Gly in specific chain of residues (fibrinogen–>fibrin)

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17
Q

What enzyme is involved in blood coagulation cascade?

A

Thrombin

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18
Q

What are zymogens?

A

Inactive form of an enzyme

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19
Q

What affects the catalytic activity ?

A

Cofactors + coenzymes

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20
Q

What can cofactors do ?

A

Execute chemical reactions that AA cannot

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21
Q

Apoenzyme?

A

An enzyme without its cofactor

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22
Q

Holoenzyme?

A

When an enzyme has a cofactor

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23
Q

Give examples of co-factors?

A

-Simple inorganic ions = Zn , Cu , Fe

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24
Q

How do simple inorganic ions promote enzyme function?

A

Make it fold + create an active site

-Enhance the charge in the AS to improve binding

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25
Q

Give an example of a simple inorganic ion cofactor promoting enzyme function?

A

Amylase requires chloride ion

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26
Q

What are co-enzymes?

A

Small organic molecules that attach + detach the enzyme when the reaction is completed to DEACTIVATE THE ENZYME

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27
Q

Example of co-enzyme?

A

Vitamins = Niacin, Riboflavin

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28
Q

What do coenzymes actually do?

A

Act as transporters of chemical groups from one reactant to another

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29
Q

What is Hurler syndrome?

A

Abnormal bone structure + development delay

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30
Q

What type of disease is Hurler Syndrome?

A

Lysosomal storage disease

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31
Q

What causes Hurler Syndrome?

A

Deficiency of iduronidase (genetic defect)

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32
Q

What does iduronidase do?

A

Degrade mucopolysaccharides in lysosomes

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33
Q

If you cannot degrade the mucopolysaccharides in lysosomes what happens?

A

There’s a build-up of glycosaminoglycan heparan sulfate (long chain sugar molecule found in mucus + fluid around the joints)

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34
Q

How d-o you treat Huo0p—rler Syndrome?

A

Enzyme replacement therapy + bone marrow replacement

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35
Q

?What is the most severe Hurler , Hurler-scheie , Scheie

A

Hurler

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36
Q

What is Niemann-Pick disease?

A

An inherited disease that affects lipid metabolism

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37
Q

What do you lack in Niemann-Pick disease?

A

Lack in sphingomyelinase ASM

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38
Q

What is sphingomyelinase needed for?

A

To metabolise the lipid sphingomyelin causing accumulation = cell death + malfunction of major organ systems

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39
Q

What is missing in Tay-Sachs disease?

A

Functional Hexosaminidase A from lysosomes

40
Q

What does the lacking of Hexosaminidase A do?

A

Progressive deterioration of nerve cells = commences at 6 months of age + death at age 4

41
Q

What accumulates without Hexosaminidase A?

A

The fatty lipid GM2 = ganglioside (especially in the nerve cells of the brain)

42
Q

How can u spot Tay-Sachs ?

A

Cherry red spot in retina

43
Q

What causes Homocystinuria?

A

Mutations in the CBS genes

44
Q

What does Cystathionine beta-synthase do?

A

Converting AA homocysteine —> cystathionine ,so methionine is produced

45
Q

What does the mutation of the CBS gene do?

A

Prevent homocysteine from being used properly —> AA + toxic by-products build-up in the BLOOD

46
Q 
What are the distribution of enzymes?
1
2
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A 
Oxidoreductases
Transferases
Hydrolases
Lysases
Isomerases
Ligases
47
Q

Examples of hydrolase?

A

Lipase , protease

48
Q

Oxidoreductase example + description?

A

Transfer e-/h = dehydrogenases , oxidases

49
Q

Isomerase description + example?

A

Rearrangement of atoms = phospohexoisomerase

50
Q

Lyase description + example?

A

Splitting chemicals into smaller parts without water = decarboxylases , aldolases

51
Q

Transferase description + example?

A

Moving functional group = Kinases , transaminases

52
Q

What do oxidoreductases do?

A

Catalyse oxidation/reduction reactions

53
Q

What adds hydroxyl groups to a substrate?

A

Hydroxylases

54
Q

Intramolecular oxygen = H/e- acceptor?

A

Oxidases

55
Q

Reduction of H2O2 + hydroperoxides?

A

Peroxidases

56
Q

Catalyse reduction?

A

Reductases

57
Q

Incorporate intramolecular O2 into organic substrates?

A

Oxygenates

58
Q

Oxidise a substrate by transferring one / more hydride ion?

A

Dehydrogenases

59
Q

What do transferases do?

A

Catalyse the movement of a functional group

60
Q

What functional group can transferases move?

A

Phosphate , methyl + glycosyl

61
Q

What does kinases do?

A

Catalyse the transfer of phosphate groups to specific substrates (phosphorylation)

62
Q

What do lyases do?

A

Catalyse the breaking of chemical bonds forming new double bonds + new ring structure

63
Q

Cleave an alcohol?

A

Aldolases

64
Q

Remove O2 / H from organic substrates in the form of H20?

A

Dehydratases

65
Q

Add / remove carboxyl groups?

A

Carboxylases

66
Q

What do ismoerases do?

A

Catalyse structural changes within a molecule

67
Q

Why is there only a change in shape with isomerases?

A

There is only 1 substrate + one product = nothing gained / lost

68
Q

Example of isomerase reaction?

A

Glucose-6-phosphate —> fructose-6-phosphate

69
Q

What do ligases do?

A

Catalysis of ligation (joining of 2 substrates)

70
Q

What does ligases use up?

A

Potential energy = coupled to hydrolysis of a diphosphate bond in a nucleotide triphosphate e.g. ATP

71
Q

Example of ligase?

A

DNA ligase

72
Q

What bonds do Nucleases cleave?

A

Phosphodiester bonds between nucleotide subunits in nucleic acids

73
Q

Endo cut in the ……

A

middle on the chain

74
Q

Exo cut in the …….

A

End of the chain

75
Q

What factors affect Enzyme-catalysed reaction?

A 
Substrate conc
Enzyme conc
Temp
pH
Inhibitors
End product inhibition
76
Q

Trypsin optimum pH

A

8

77
Q

Pepsin optimum pH

A

2

78
Q

What is enzyme kinetic?

A

The study of the rate of an enzyme controlled reaction

79
Q

The michaelis-menten?

A

Vo=Vmax[S]
————
Km + [S]
Vmax = max velocity = saturating substrate conc
Km = the substrate conc at which the reaction velocity is 50% of the Vmax
[S] = the conc of substrate S

80
Q

What is Km a useful measure of?

A

The affinity of E for S

81
Q

What does low Km = ?

A

A high affinity of enzyme for S , so fast reaction at low S

82
Q

What does high Km = ?

A

Lower affinity of substrate

83
Q

How do ACE inhibitors work?

A

Inhibit formation of angiotensin II = lower blood pressure

84
Q

Important enzyme inhibitors?

A

Zymogens

85
Q

Example of competitive inhibitors ?

A

Disulfiram (Antabuse) inhibits Aldehyde Oxidase = accumulation of acetaldehyde —> nausea/vomit (acute sensitivity of ethanol 4 alcoholism)

86
Q

Example of Non-competitive (allosteric) inhibition?

A

Alter the configuration of the AS = inactive enzyme —> no competition

87
Q

Example of Non-competitive inhibitor?

A

Nifedipine = calcium channel blocker (inhibits Ca+ dependent ATPase) —-> prevents uptake of Ca into cardiac cells (needed 4 cardiac muscle excitation)

88
Q

What is Nifedipine used for?

A

Angina + high blood pressure

89
Q

What do Irreversible inhibitors do?

A

Bind SO TIGHTLY to the enzyme (covalent bond) they can’t be removed

90
Q

Name Irreversible inhibitors and what they do?

A

Sarin - binds to serine residue in acetylcholinesterase = prevent nerve transmission

Aspirin - covalently modifies prostaglandin H2 synthase = reducing synthesis of inflammatory signals

91
Q

How does Uncompetitive inhibitors affect Vmax + Km?

A 
Vmax = decrease
Km = decrease
92
Q

What does Uncompetitive inhibitors bind to?

A

The enzyme substrate complex

93
Q

Why are end-product inhibition important?

A

Important control for complex multi-step processes

94
Q

How do zymogens act as inhibitors?

A

Enzymes are initially produced as an inactive precursor form

95
Q

Describe the structure of zymogens?

A

Typically a longer polypeptide that must be HYDROLYZED at a specific location to produce the active form of the enzyme

96
Q

If there’s a cleavage at the AS with zymogens what happens + example?

A

Release of polypeptide known as the “pro-sequence” + results in the activation of the enzyme
-Pepsinogen —> pepsin

97
Q

What can further regulate enzyme activity?

A

Gene expression
Phosphorylation
Proteolysis

Alia - Biology (10 decks)

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