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biochemistry > Chapter 8 - Enzymes > Flashcards

Chapter 8 - Enzymes Flashcards

(65 cards)

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1
Q

All Enzymes are what?

A

Catalysts but not all catalysts are enzyme

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2
Q

In the example of a jelly fish, what does it have that is unique to it and why does it happen?

A

Jelly fish glows because of an enzyme called aequorin catalizing the oxidation.

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3
Q

Give 3 examples of Enzyme facts.

A
  1. Enzyme results in chemical transformations 2. It can transform energy from one form to another 3. Most enzymes are proteins.
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4
Q

Enzyme’s power is what.

A

Enzyme can accelerate reactions by 1mil or more.

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5
Q

What is the relationship between biological reactions and enzymes?

A

Most biological reactions will not work without enzymes.

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6
Q

Give an example of the fastest enzyme known.

A

Hydrates does 10^6 molecules of CO2 per sec.

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7
Q

True or False: Enzymes are not specific and can catalyze any substrates available.

A

False. Enzymes are specific regarding both reactions & substrates.

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8
Q

What selectivity characteristics does an enzyme have?

A

Enzymes sometimes can catalyze one reaction and there are some that can catalyze multiple reactions that are similar.

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9
Q

What is proteolytic?

A

Proteolytic enzymes breaks down polypeptide chains into smaller ones.

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10
Q

Give an example of proteolytic.

A

Papain cleaves any peptide bond.

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11
Q

The specificity of an enzyme is dependent on what?

A

Specificity of an enzyme is dependent on the substrate enzyme interaction. Also, 3D forms dictates function.

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12
Q

Some enzymes cannot work without being help by what?

A

Cofactors

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13
Q

What are apoenzymes?

A

Apoenzymes work without cofactors

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14
Q

What is a Haloenzymes

A

Enzymes activated by a cofactor.

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15
Q

List different types of cofactors

A
  1. Metals 2. Small organic molecules
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16
Q

Under small organic molecules cofactors what are the two different categories?

A

Tightly bound and Loosely bound.

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17
Q

One specific type of function that enzymes can help is what?

A

our bodies need to convert energy and enzyme helps to convert them. Ex. production of ATP from glycolysis needs enzymes hexokinase and phosofructokinase.

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18
Q

Enzymes speed up the rate of reactions but what is it’s relationship with delta G

A

Enzymes do not change or alter free energy is not dependent on it.

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19
Q

So what does enzyme affect.

A

Enzymes only affect the energy to start a reaction or the activation energy. Lowers the transition state.

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20
Q

True or False: Delta G is dependent on mech/pathway of the reaction.

A

False. Delta G does not depend on the path it takes for the product to be produced.

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21
Q

What can you say about the relationship between Delta G and rate of reaction

A

Delta G tells us nothing about the rate. Even if Delta G is negative, we don’t know if the reaction is fast or slow.

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22
Q

What does rate of reaction depend on?

A

Activation energy

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23
Q

Is Delta G related to Equilibrium constant?

A

yes

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24
Q

Keq in standard condition is what?

A

[Products][Reactants]=Keq

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25
What is the equation of Delta G?
Delta G Prime=-RTlnKeq
26
Delta G affects the reaction in what way?
Delta G determines if the reaction will happen, spontaneous or non-spontaneous.
27
What are some facts about enzyme and reaction rate regarding thermodynamic and equilibrium?
Enzymes cannot alter thermodynamics or equilibrium. Enzymes accelerate the rate or attainment of equilibrium not the direction of it.
28
What can you say about transition state of a reaction?
Transition state is least stable and have a very high energy.
29
Enzymes combines with what to form what?
Enzymes come together with substrates to form enzyme-substrate complex.
30
Where do substrate bind on the enzyme?
The substrate binds on the active site, usually a pocket.
31
What is max velocity?
Max velocity is when all enzymes have all their active sites filled.
32
How does active sites work on the enzyme?
Active sites have amino acid residues that help bind the substrate.
33
How are these 3D cleft or crevice form in an active site?
They are formed by different parts of the amino acid chains.
34
What are the different amino acids in active sites?
Polar, non-polar and Ionic amino acids
35
How are the substrates bind to active site?
Substrates bind by multiple weak interactions.
36
Name the old and current arrangement of enzyme
The old way was Lock & Key but now it is considered as induced fit model.
37
Why do enzyme lower the activation energy?
Free energy is released when enzyme-substrate complex forms. The max binding energy release when enz-sub froms.
38
Michaelis-Menten model can do what?
It can tell the enzymes reactions.
39
Km is a measure of what?
Km is a measure of affinity. If enz has high affinity then Km is low. If enz has low affinity then Km is High.
40
How do we determine the actual values for Km?
Double recirprocal plots(Lineweaver-Burch plots)
41
Some of the Km values for enzymes.
Chymotrypsin has 5000microM Lysozyme has 6microM B-Galactosidase has 4000microM Threonine deaminase has 5000microM Carbonic anhydrase has 8000microM Penicillinase has 50microM pyruvate carboxylase has 3 400/1000/60 pyruvate / HCO3- / ATP Arginine-tRNA syntetase 3/.4/300 arginine/tRNA/ATP
42
Kcat/Km measures what?
measures catalytic efficiency. larger Kcat/Km value equals higher preference.
43
What are sequential reactions?
All substrates must bind to the enzyme before any product is formed. Can be ordered or random.
44
what are Double displacement reactions?
1 or more products released before all substrate bind.
45
Allosteric enzyme have multiple active sites, can MM quantify this?
No, MichaelisMenten cannot figure this out.
46
What does binding of one substrate do to this allosteric enzyme? (Hint: Hemoglobin)
Binding of substrate to one can alter the others.
47
Enzyme activity can be inhibited in what way?
It can be inhibited by binding small molecules and or Ions.
48
What are the 2 different categories of inhibition?
Reversible and Irreversible
49
Irriversible inhibition can become what?
They can become very tightly bound and only slowly disociates. Can be covalent or ionic.
50
What does penicillin do?
Penicillin is an irreversible inhibitor that covalently binds to transpeptidase, preventing the synthesis of bacterial cell walls.
51
What does aspirin do?
Aspirin is also an irreversible inhibitor, they covalently bind to cycloxygenase and reduces the synthesis of signaling molecules in inflamtion.
52
What is a reversible inhibition?
It rapidly dissociates
53
What are competitive inhibition?
Competitive inhibitors bind to the same active sites of substrate.
54
Can you reverse the process of competitive inhibition?
Yes, by increasing the substrate concentration.
55
What are uncompetitive inhibitor?
Uncompetitive inhibitor binds to the enz-subs complex. This cannot be overcome with the increase in substrate.
56
What are non-competitive inhibition?
Inhibitor and substrate bind at different places. Inhibitor can bind to free enz or enz-sub complex. This works by decreasing the functional concentration of the enz-sub complex. Decreases turnover. Cannot be overcome by increasing sub-concentration.
57
What does Ki equal to?
Ki = [E][I] / [EI] enz-inhib complex. Smaller Ki = more potent inhibition.
58
What are the effects of competitive inhibition?
It is to increase Km, more substrate to reach the same rate without inhibition.
59
Uncompetitive inhibitors do what exactly?
They bind only to enz-sub complex and no products are formed. Vmax= lower Km=lower
60
Non-competitive inhib kinetics are what?
Substrate still binds but no product forms. Vmax decreases and Km unchanged.
61
Double reciprocal plots shows what?
x-int = -1/km slope = Km/Vmax Yint = 1/Vmax
62
What are the 3 categories of enzyme?
Group specific, Affinity levels, Suicide inhibitors
63
What are group specifics?
they only react with specific side chains
64
What are affinity levels(reactive substrate analogs)
Structurally similar to substrate and covalently bind to the active site residues.
65
what are suicide inhibitors?
Inhibitors binds to substrate and is initially processed by the catalytic mechanism. Generates a chemically reactive intermediate that inactivates the enzyme.

biochemistry (4 decks)

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