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Biochemistry > Lecture 4: Enzymes > Flashcards

Lecture 4: Enzymes Flashcards

1
Q

What are a few reasons to use proteins as catalysts?

A

Milder Conditions

Higher reaction rates

Greater reaction specificity

Capacity for regulation

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2
Q

Are enzymes globular proteins?

A

Yes;

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3
Q

What are ribozymes

A

Enzymes that catalyze RNA reactions

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4
Q

What is the name of the molecule that is catalyzed?

A

Substrate

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5
Q

True or False; Active site residues also contribute to substrate specificity

A

True

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6
Q

What does ES stand for?

A

Enzyme- Substrate (Complex)

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7
Q

What is the top of the energy hill?

A

Transition State

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8
Q

True or False; Increase in AE (Activation Energy) decreases rate of reaction

A

True AE/ROR are opposite

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9
Q

True or False; enzyme lowers Delta G and decreases reaction rate

A

False; lower delta G= increase in reaction rate

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10
Q

Does the enzyme lower the AE?

A

Yes;

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11
Q

Does the enzyme change the reaction eq.?

A

No; it does not have effect on the equilibria

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12
Q

What is the major difference between the S & P transition state?

A

Activation Energy

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13
Q

What are (3) ways enzymes lower AE?

A

(1) Rearrange covalent bonds
(2) Bring reactive groups closer
(3) Stabilize transition state

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14
Q

What is the rate limiting step?

A

Step with the highest activation energy

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15
Q

What is the formation and decay of transient chemical species?

A

Reaction Intermediates

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16
Q

How do you stabilize the transition state?

A

Form weak covalent bonds bt. enzyme and substrate to lower activation energy?

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17
Q

True or false; Different energies are used to for catalysis and enzyme specificity

A

False; same energy is used in both.

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18
Q

The E-site is used to form a variety of ______ interactions.

A

Weak interactions

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19
Q

What is kinetics?

A

Study of the rate at which compounds react

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20
Q

Are irreversible inhibitors promiscuous?

A

Yes; they are toxic and bind to anything (sleep with everyone)

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21
Q

How are reversible inhibitors used as drugs?

A

slow down a specific enzyme

22
Q

What are (2) ways in which reversible inhibitors bind?

A

(1) free enzyme and prevent the binding of the substrate

(2) enzyme-substrate complex and prevent the reaction

23
Q

What are (3) types of inhibition?

A

(1) Competitive
(2) Uncompetitive
(3) Noncompetitive (mixed)

24
Q

True or false: Kd=Km

A

True

25
Q

What is 1/Ka?

A

Kd (disassociation constant)

26
Q

What does Competitive Inhibition bind to?

A

Active Site of Free Enzyme

27
Q

What is Competitive Inhibition Km & Affinity?

A

Km increases

Affinity decreases

28
Q

What is Competitive Inhibition y-max & Vmax?

A

stays the same

29
Q

What does Non-Competitive Inhibition bind to?

A

Active site of the free enzyme

ES complex and varying affinity

30
Q

What does Un-Competitive Inhibition bind to?

A

Allosteric Site of ES Complex

31
Q

What happens to the Km and Affinity of Un-Competitive?

A

Km- decreases

Affinity- Increases

32
Q

What happens to the y-max and v=man of Un-Competitive?

A

They both decrease

33
Q

What is another name for irreversible inhibitors

A

Suicide substrate

34
Q

Describe Competitive Inhibition Graph

A

Lines intersect at y-axis

35
Q

Describe Uncompetitive Inhibition Graph

A

Lines are parallel

36
Q

What is another name for mixed inhibition

A

Non-competitive

37
Q

Where does covalent modification occur?

A

Irreversible Inhibtion

38
Q

Describe Mixed Inhibition Graph

A

Lines intersect at y-axis

39
Q

What is a protease?

A

Enzyme that cleaves peptides on the C-terminal side of Aromatic AA’s.

40
Q

True or False; Proteases hydrolyze the peptide bond

A

True

41
Q

What are the three AA that make up the Catalytic Triad

A

Ser195

His57

ASP102

42
Q

In general base catalysis, what extracts the proton?

A

Amino Acid extracts the proton

43
Q

In general base catalysis, AA acts as a _____ removing___ from H2).

A

Base; Proton

44
Q

What is removed from H2O in AA catalysis?

A

-OH

45
Q

What (2) items must we remember about General-Base Catalysis?

A

(1) Protein Extraction by a weak base

(2) Typically via groups other than -OH from water

46
Q

What is General Acid Catalysis

A

AA donates a proton

47
Q

Where is peptidoglycan found?

A

Cell Walls

48
Q

What type of enzyme is lysozyme?

A

antibacterial enzyme

49
Q

Dehydration of Lys345 forms what?

What enzyme does that

A

Double Bond; Enolase

50
Q

Use of which inhibitors make the max seem lower when inhibitor is not present

A

Non-competitive/mixed

51
Q

Use of which inhibitor make the max seem lower when inhibitor is present?

A

None; max is never high

52
Q

Use of which Inhibitor-affinity of enzyme for substrate increases

A

Un-Competitive

Biochemistry (12 decks)

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