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Biochemistry Module 2 > Chapter 7 Enzyme : Mechanism of Action > Flashcards

Chapter 7 Enzyme : Mechanism of Action Flashcards

1
Q

True or False. When an enzyme binds substrate molecules at its active site, it creates a region of high local substrate concentration.

A

True

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2
Q

A catalysis mechanism where functional groups of aminoacyl side chains & prosthetic groups contribute to catalysis by acting as acid/base.

A

Acid-Base Catalysis

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3
Q

Rate of reaction is sensitive to changes in the concentration of OH and H3O only.

A

Specific Acid-Base Catalysis

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4
Q

Acid or Base. Proton donors?

A

Acids

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5
Q

Acid or Base. Proton acceptors?

A

Base

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6
Q

Rate of reaction is responsive to all acids/bases present

A

General Acid-Base Catalysis

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7
Q

A catalysis mechanism that involves breaking a covalent bind -> binding of substrate (conformation) -> weakening of bond -> undergo cleavage

A

Catalysis by Strain

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8
Q

A transient species that represents that transition state, or half-way point, in the transformation of substrates to products

A

Transition State Intermediate

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9
Q

First person to suggest a role of transition state stabilization as a general mechanism by which enzymes accelerate the rates of chemical reactions

A

Nobel Laureate Linus Pauling

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10
Q

A catalysis mechanism stating that “the higher the molecule concentration, the more frequent they will encounter one another leading to greater rate of reaction”.

A

Catalysis by Proximity

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11
Q

Effective enzyme inhibitors as potential pharmacophores

A

Transition State Analogs

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12
Q

A catalysis mechanism where there is a formation of covalent bond between one or more substrate and enzyme (becomes a reactant)

A

Covalent Catalysis

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13
Q

A catalysis mechanism where it introduces a new reaction pathway with a lower activation energy thus making the reaction faster in a homogenous solution

A

Covalent Catalysis

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14
Q

A catalysis mechanism where chemical modification of enzyme is transient (not long lasting). It is where completion of reaction returns the enzyme to its original state

A

Covalent Catalysis

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15
Q

A catalysis mechanism common among enzymes that catalyze group transfer reactions

A

Covalent Catalysis

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16
Q

Highly conserved residues on enzyme that participated in Covalent Catalysis

A

Cysteine, Serine and Histidine (occassionally)

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17
Q

The mechanism followed by Covalent Catalysis, one in which the first substrate is bound and its product released prior to the binding of the second substrate

A

“Ping Pong” Mechanism

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18
Q

Non-protein enzymes

A

Ribosomal RNAs and Ribozymes

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19
Q

Self-cleaving/self-splicing RNA molecules

A

Ribozymes

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20
Q

A characteristic of enzyme where it is neither consumed nor permanently altered as a consequence of participation in a reaction

A

Effectivity

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21
Q

A characteristic of enzyme where it catalyzes reactions of only one stereoisomer

A

Stereospecificity

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22
Q

Enzymes bind substrates to at least “__________” converting non-chiral to chiral products

A

Three-point of Attachment

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23
Q

Developed an unambiguous system of enzyme nomenclature

A

International Union of Biochemist (IUB)

Ref. Harper’s 29th Edition Chapter 8 page 58

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24
Q

Enzymes that catalyze oxidations (losing of electrons) and reductions (gaining of electrons)

A

Oxidoreductase

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25
Q

Enzymes that catalyze transfer of moieties (two equal parts) such as functional groups from one substrate to another (may be anabolic)

A

Transferases

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26
Q

Enzymes that catalyze hydrolytic cleavage of C-C, C-O, C-N and other covalent bonds (catabolic)

A

Hydrolases

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27
Q

Enzymes that catalyze cleavage of C-C, C-O, C-N and other covalent bonds by atom elimination, generating double bonds (catabolic)

A

Lyases

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28
Q

Enzymes that catalyze geometric or structural changes within a molecule (neither catabolic nor anabolic)

A

Isomerases

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29
Q

Enzymes that catalyze joining together of 2 molecules in reactions (anabolic) coupled to the hydrolysis of ATP

30
Q

6 Classes of Ezymes

A

Oxidoreductases, Hydrolases, Tranferases, Lyases, Ligases, Isomerases

31
Q

4 General Mechanisms to Facilitate Catalysis

A

Proximity, Acid-Base, Strain and Covalent Catalysis

32
Q

Nonprotein molecules and metal ions that participate directly in substrate binding or in catalysis

A

Prosthetic Groups, Cofactors, Coenzymes

33
Q

Tightly and stably incorporated into a protein’s (enzyme) structure by covalent or noncovalent forces

A

Prosthetic Group

34
Q

Most common prosthetic group; participate in redox reactions, facilitate binding and orientation of substrates, formation of covalent bonds with reaction intermediates or acts as Lewis acids or bases

A

Metal Ions

35
Q

Electrophilic or Nucleophilic. Electron-poor?

A

Electrophilic

36
Q

Electrophilic or Nucleophilic. Electron-rich?

A

Nucleophilic

37
Q

Associate reversibly or binds in a transient, dissociate matter to the enzymes/substrate such as ATP and participates in catalysis

38
Q

Serves as recyclable shuttles/group transfer agents of substrates from one point within the cell to another

39
Q

Twofold Function of Coenzymes as Shuttles

A
  1. Stabilize species (eg. hydrogen atoms and hydride ions)

2. Serve as an adaptor or handle (facilitates recognition and binding of small chemical group; eg. acetate/coenzyme A)

40
Q 
Which of the following is a Ribozyme?
A. Vitamin B
B. DNA & RNA
C. Protein
D. Hammerhead
A

D. Hammerhead

41
Q

What are the 4-digit IUBMB definition of an enzyme? (Ex. Alcohol Dehydrogenase Alcohol: NAD+ Oxidoreductase EC 1.1.1.1)

A

Major Class: Enzyme Group
Subclass: Mechanism
Sub-sub Class: Substrate Class
Specific Substrate

42
Q

A cleft or pocket on the enzyme where catalysis occurs. It also binds/shields substrates & cofactors.

A

Active Site

43
Q

Who propose the “Lock and Key” Model?

A

Emil Fischer

44
Q

What model states that enzymes and its substrates interact to form an enzyme-substrate (ES) complex?

A

Lock and Key Model

45
Q

The model that states that there is a reciprocal changes in both substrate and enzyme structure upon binding.

A

Induce Fit Model

46
Q

Who propose the Induce Fit Model (Hand-Glove Fitting)?

A

Daniel Koshland

47
Q

True or False. Interactions that preferentially bind the transition state increases its concentration therefore proportionally decreases the reaction rate.

A

False. It increases the reaction rate.

48
Q

What fits the active site best?

A

Substrate induced to take up a configuration approximating the transition state.

49
Q

The binding of _____, in general induces a major conformational change in the enzyme.

A

Glucose or hexoses

50
Q

What consist an active holoenzyme (an enzyme with its required cofactor)?

A

Inactive apoenzyme (an enzyme that lacks a needed cofactor) and non-protein co-factor

51
Q

What is the the enzyme of Thiamine pyrophosphate & Flavin Adenine Nucleotide?

A

Pyruvate dehydrogenase & Monoamine Oxidase

52
Q

What is the the enzyme of Nicotinamide Adenine Dinucleotide & Pyridoxal Phosphate?

A

Lactate Dehydrogenase & Glycogen Phosphorylase

53
Q

What is the the enzyme of Coenzyme A (CoA) & Biotin?

A

Acetyl Coa Carboxylase & Pyruvate Carboxylase

54
Q

What is the the enzyme of 5’-Deoxyadenosyl Cobalamin & Tetrahydrofolate?

A

Methylmalonyl Mutase z& Thymidylate Synthase

55
Q

Between Chymotrypsin and HIV-protease, who illustrates ACID-BASE CATALYSIS?

A

HIV-Protease. (Chymotrypsin as well as Fructose-2, 6-Biphosphatase illustrate COVALENT CATALYSIS)

56
Q

Proteins that diverged from a common ancestor are said to be ______ to one another.

A

Homologous

57
Q

They are distinct enzyme forms that catalyze the same reaction.

58
Q

True or False. The rate of catalytic reaction being monitored is proportionate to the amount of enzyme present.

59
Q

True or False. Proteins from the cytoplasm tend to appear more slower than those from subcellular organelles.

A

False. It appears more rapidly.

60
Q

Serum enzyme used to diagnose ACUTE PANCREATITIS.

A

Amylase and Lipase

61
Q

Serum enzyme used to diagnose LIVER DISEASES.

A

Lactate dehydrogenase isozyme 5

62
Q

Serum enzyme used to diagnose Wilson’s disease (Hepatolenticular degeneration).

A

Ceruloplasmin

63
Q

Which of the following is a tetrameric enzyme consisting of 2 monomer types and offers the advantage of tissue specificity as a consequece of its quaternary structure?

A. Lactate dehydrogenase (LDH)
B. SGOT
C. Alanine aminotransferase
D. Aspartate aminotransferase

A

Lactate dehydrogenase. It has 2 monomers: H (for heart) and M (for muscle) that combine to yield five LDH isozymes.

64
Q

What LDH isozyme predominates in the heart?

A

Isozyme I(1)

65
Q

What LDH isozyme predominates in the muscles?

A

Isozyme I(5)

66
Q

CK-MB has a useful diagnostic window for MI because it appears within ______hours, peaks at ______hours and returns to baseline by _______hours.

A

Appears within 4-6H, peaks at 24H, and returns to baseline by 48-72H.

67
Q

What is the preferred diagnostic marker for MI, which is a complex structure of 3 proteins involve in skeletal and cardiac muscle contraction excluding smooth muscle?

68
Q

Troponin levels rise for ______H after an MI and remain elevated for ______days.

A

2-6H and 4-10 days

69
Q

Who discovered the first catalytic RNA molecule?

A

Thomas Cech

70
Q

Many coenzymes, cofactors and prosthetic groups are derivatives of _____?

A

B Vitamins

Biochemistry Module 2 (3 decks)

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