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Alia - Biology > Lecture 10-Enzymes > Flashcards

Lecture 10-Enzymes Flashcards

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
Give an example of a simple inorganic ion cofactor promoting enzyme function?
Amylase requires chloride ion
26
What are co-enzymes?
Small organic molecules that attach + detach the enzyme when the reaction is completed to DEACTIVATE THE ENZYME
27
Example of co-enzyme?
Vitamins = Niacin, Riboflavin
28
What do coenzymes actually do?
Act as transporters of chemical groups from one reactant to another
29
What is Hurler syndrome?
Abnormal bone structure + development delay
30
What type of disease is Hurler Syndrome?
Lysosomal storage disease
31
What causes Hurler Syndrome?
Deficiency of iduronidase (genetic defect)
32
What does iduronidase do?
Degrade mucopolysaccharides in lysosomes
33
If you cannot degrade the mucopolysaccharides in lysosomes what happens?
There's a build-up of glycosaminoglycan heparan sulfate (long chain sugar molecule found in mucus + fluid around the joints)
34
How d-o you treat Huo0p---rler Syndrome?
Enzyme replacement therapy + bone marrow replacement
35
?What is the most severe Hurler , Hurler-scheie , Scheie
Hurler
36
What is Niemann-Pick disease?
An inherited disease that affects lipid metabolism
37
What do you lack in Niemann-Pick disease?
Lack in sphingomyelinase ASM
38
What is sphingomyelinase needed for?
To metabolise the lipid sphingomyelin causing accumulation = cell death + malfunction of major organ systems
39
What is missing in Tay-Sachs disease?
Functional Hexosaminidase A from lysosomes
40
What does the lacking of Hexosaminidase A do?
Progressive deterioration of nerve cells = commences at 6 months of age + death at age 4
41
What accumulates without Hexosaminidase A?
The fatty lipid GM2 = ganglioside (especially in the nerve cells of the brain)
42
How can u spot Tay-Sachs ?
Cherry red spot in retina
43
What causes Homocystinuria?
Mutations in the CBS genes
44
What does Cystathionine beta-synthase do?
Converting AA homocysteine ---> cystathionine ,so methionine is produced
45
What does the mutation of the CBS gene do?
Prevent homocysteine from being used properly ---> AA + toxic by-products build-up in the BLOOD
46
``` What are the distribution of enzymes? 1 2 3 4 5 6 ```
``` Oxidoreductases Transferases Hydrolases Lysases Isomerases Ligases ```
47
Examples of hydrolase?
Lipase , protease
48
Oxidoreductase example + description?
Transfer e-/h = dehydrogenases , oxidases
49
Isomerase description + example?
Rearrangement of atoms = phospohexoisomerase
50
Lyase description + example?
Splitting chemicals into smaller parts without water = decarboxylases , aldolases
51
Transferase description + example?
Moving functional group = Kinases , transaminases
52
What do oxidoreductases do?
Catalyse oxidation/reduction reactions
53
What adds hydroxyl groups to a substrate?
Hydroxylases
54
Intramolecular oxygen = H/e- acceptor?
Oxidases
55
Reduction of H2O2 + hydroperoxides?
Peroxidases
56
Catalyse reduction?
Reductases
57
Incorporate intramolecular O2 into organic substrates?
Oxygenates
58
Oxidise a substrate by transferring one / more hydride ion?
Dehydrogenases
59
What do transferases do?
Catalyse the movement of a functional group
60
What functional group can transferases move?
Phosphate , methyl + glycosyl
61
What does kinases do?
Catalyse the transfer of phosphate groups to specific substrates (phosphorylation)
62
What do lyases do?
Catalyse the breaking of chemical bonds forming new double bonds + new ring structure
63
Cleave an alcohol?
Aldolases
64
Remove O2 / H from organic substrates in the form of H20?
Dehydratases
65
Add / remove carboxyl groups?
Carboxylases
66
What do ismoerases do?
Catalyse structural changes within a molecule
67
Why is there only a change in shape with isomerases?
There is only 1 substrate + one product = nothing gained / lost
68
Example of isomerase reaction?
Glucose-6-phosphate ---> fructose-6-phosphate
69
What do ligases do?
Catalysis of ligation (joining of 2 substrates)
70
What does ligases use up?
Potential energy = coupled to hydrolysis of a diphosphate bond in a nucleotide triphosphate e.g. ATP
71
Example of ligase?
DNA ligase
72
What bonds do Nucleases cleave?
Phosphodiester bonds between nucleotide subunits in nucleic acids
73
Endo cut in the ......
middle on the chain
74
Exo cut in the .......
End of the chain
75
What factors affect Enzyme-catalysed reaction?
``` Substrate conc Enzyme conc Temp pH Inhibitors End product inhibition ```
76
Trypsin optimum pH
8
77
Pepsin optimum pH
2
78
What is enzyme kinetic?
The study of the rate of an enzyme controlled reaction
79
The michaelis-menten?
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
What is Km a useful measure of?
The affinity of E for S
81
What does low Km = ?
A high affinity of enzyme for S , so fast reaction at low S
82
What does high Km = ?
Lower affinity of substrate
83
How do ACE inhibitors work?
Inhibit formation of angiotensin II = lower blood pressure
84
Important enzyme inhibitors?
Zymogens
85
Example of competitive inhibitors ?
Disulfiram (Antabuse) inhibits Aldehyde Oxidase = accumulation of acetaldehyde ---> nausea/vomit (acute sensitivity of ethanol 4 alcoholism)
86
Example of Non-competitive (allosteric) inhibition?
Alter the configuration of the AS = inactive enzyme ---> no competition
87
Example of Non-competitive inhibitor?
Nifedipine = calcium channel blocker (inhibits Ca+ dependent ATPase) ----> prevents uptake of Ca into cardiac cells (needed 4 cardiac muscle excitation)
88
What is Nifedipine used for?
Angina + high blood pressure
89
What do Irreversible inhibitors do?
Bind SO TIGHTLY to the enzyme (covalent bond) they can't be removed
90
Name Irreversible inhibitors and what they do?
Sarin - binds to serine residue in acetylcholinesterase = prevent nerve transmission Aspirin - covalently modifies prostaglandin H2 synthase = reducing synthesis of inflammatory signals
91
How does Uncompetitive inhibitors affect Vmax + Km?
``` Vmax = decrease Km = decrease ```
92
What does Uncompetitive inhibitors bind to?
The enzyme substrate complex
93
Why are end-product inhibition important?
Important control for complex multi-step processes
94
How do zymogens act as inhibitors?
Enzymes are initially produced as an inactive precursor form
95
Describe the structure of zymogens?
Typically a longer polypeptide that must be HYDROLYZED at a specific location to produce the active form of the enzyme
96
If there's a cleavage at the AS with zymogens what happens + example?
Release of polypeptide known as the "pro-sequence" + results in the activation of the enzyme -Pepsinogen ---> pepsin
97
What can further regulate enzyme activity?
Gene expression Phosphorylation Proteolysis

Alia - Biology (10 decks)

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