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Biochem Module 2 > 2: Enzymes > Flashcards

2: Enzymes Flashcards

0
Q

The term enzyme is from what Greek word that means leavened (yeast)

A

Enzmos

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1
Q

Biologic polymers that catalyze the chemical reactions that make life.

A

Enzymes

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2
Q

A handful of self-cleaving RNA molecules which are known as:

A

Ribozymes

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3
Q

What are the vast majority of enzymes made of?

A

Proteins

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4
Q

This is where catalysis occurs and what forces the substrate to resemble transition state.

A

Active site

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5
Q

True or false: Enzymes are NOT hormones.

A

TRUE

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6
Q

Give 3 characteristics of enzymes as catalyst.

A
  1. Make rxn go faster (by at least 10 raised to the 6th)
  2. Not be consumed in rxn
  3. Not change the thermodynamics
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7
Q

Physically distinct versions of enzymes that catalyze the same rxn, and provides back-up copy of essential enzyme.

A

Isozymes

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8
Q

When we say part of an enzyme, this refers to substrate or active site?

A

Active site

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9
Q

Reactant would pertain to:

A

Substrate

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10
Q

The active site fits the substrate like a key fitting into its lock.

A

Lock and key model

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11
Q

Alterations in the active site as enzymes & substrates bind.

A

Induced fit model

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12
Q

Has active site & substrate.

A

Complementarity

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13
Q

Job done with the least possible energy.

A

Efficiency

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14
Q

The enzymes limited to specific locations.

A

Compartmentalization

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15
Q

For each enzyme, only a few substrates and only one rxn is catalyzed.

A

Specificity

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16
Q

Actions of enzyme are controlled by other substrates.

A

Regulated

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17
Q

Give 2 reasons for compartmentalization.

A

Protection vs inhibitors

Promote favorable environment

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18
Q

What are the substances required for enzyme function?

A

Prosthetic groups
Cofactors
Coenzymes

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19
Q

Known as substrate shuttles.

A

Coenzymes

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20
Q

With transient, dissociable attachment to enzyme.

A

Cofactors

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21
Q

With tight & stable attachment to the enzyme.

A

Prosthetic groups

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22
Q

A holoenzyme is composed of:

A

Enzyme + cofactor

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23
Q

Composed of enzyme only.

A

Apoenzyme

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24
Q

Name the 4 mechanisms for enhanced catalysis.

A

Catalysis by proximity
Acid base catalysis
Catalysis by strain
Covalent catalysis

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25
Q

Mechanism of catalysis due to ionizable aminoacyl side chains or prosthetic groups.

A

Acid-base catalysis

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26
Q

Mechanism of catalysis by conformational change that weakens covalent bond.

A

Catalysis by strain

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27
Q

When the enzyme is temporarily a reactant, and when cysteine, serine, histidine form transient covalent bond.

A

Covalent catalysis

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28
Q

When there is creation of a region of high substrate conc once binding begins.

A

Catalysis by proximity

29
Q

The ‘new school’ enzyme naming is by the:

A

International Union of Biochemists

30
Q

What can be used for the enzymes first name in the ‘old school’?

A

Substrate
Source of enzyme
A feature of its MOA

31
Q

The ________ name is based on the rxn catalyzed by enzyme followed by the suffix -ase

A

Second

32
Q

Enzyme classification: joining of two molecules coupled to hydrolysis of ATP

A

Ligases

33
Q

It transfers moieties such as glycosyl, methyl, phosphoryl groups.

A

Transferase

34
Q

It cleaves C-C, C-O, C-N & other bonds by atom elimination, leaving double bonds.

A

Lyases

35
Q

What catalyzes geometric or structural changes w/in molecule?

A

Isomerase

36
Q

Hydrolytic cleavage of C-C, C-O, C-N & other bonds.

A

Hydrolase

37
Q

What catalyzes redox rxns?

A

Oxidoreductase

38
Q

Deals w/ quantitative measurement of rates of enzyme-catalyzed rxns.

A

Enzyme kinetics

39
Q

True or false: Enzyme kinetics plays a central role in drug discovery.

A

TRUE

40
Q

It predicts whether a rxn will proceed spontaneously or is favorable & energy available to do work.

A

Gibbs free energy

41
Q

True or false: The natural & favorable tendency for processes is to proceed from an area of low energy to an area of high energy.

A

FALSE (should be from high to low)

42
Q

The reaction when there is net loss of energy, and is it spontaneous or not?

A

Exergonic rxn, YES

43
Q

Endergonic rxn pertains to the net ______ of energy.

A

Gain

44
Q

True or false: Endergonic rxn is a spontaneous rxn.

A

FALSE

45
Q

Characteristics of a standard free energy charge:

A

(Reac) & (prod): 1 molar
Temp: 25 degress Celcius/298 K
Pressure: 1 atmosphere

46
Q

Law used for coupling rxn:

A

Hess law (energy of consecutive rxns are additive)

47
Q

A rxn w/ a positive net G may still yield an overall negative free energy change if it is coupled to another rxn w/ ____________. This is an implication of what?

A

large negative net G, Hess law

48
Q

If the net energy is equal to 0:

A

Equilibrium

49
Q

What are the effects of enzymes on Gibbs free energy?

A

Lower free energy of activation
Do not change the energy of reactants & products
Do not change equilibrium rxn

50
Q

What are the factors affecting “collision”?

A

Substrate concentration
Temperature
pH
Inhibitors

51
Q

For 2 molecules to react this theory is applies:

A

Kinetic theory/Collide theory (possess enough energy to overcome energy barrier to reach transition state)

52
Q

Increase substrate concentration will have what effect on reaction rate?

A

Increase

53
Q

Relates reaction rate to substrate concentration:

A

Michaelis-menten equation

54
Q

What kind of curve shows Michaelis-menten kinetics & shows saturability?

A

Hyperbolic curve

55
Q

How fast the reaction is:

A

Initial velocity

56
Q

When there is low substrate affinity the Michaelis constant is

A

High

57
Q

Michaelis constant (Km) is ________ proportional to substrate affinity.

A

Inversely

58
Q

The maximal number of substrate molecules converted to product per unit time:

A

Maximum velocity

59
Q

First order kinetics with rate directly proportional to [s]?

A

Below Km

60
Q

It is the reciprocal of the Michaelis-Menten equation:

A

Lineweaver-Burke plot

61
Q

Kinetics above Km in which rate is not affected by [s]:

A

Zero order kinetics

62
Q

Used to determine the mechanism of action of enzyme inhibitors and to calculate Km and Vmax:

A

Lineweaver-burke plot

63
Q

The equation used for multimeric enzymes:

A

Hill equation

64
Q

What is the curve in the Hill equation?

A

Sigmoidal curve

65
Q

The increase in substrate will also increase enzyme activity. This is called:

A

Cooperativity

66
Q

What are the factors affecting reaction rate?

A

Temperature

pH

67
Q

If there is an increase of inhibitors, reaction rate will inc or dec?

A

Decrease

68
Q

Any substance that diminishes the velocity of an enzyme catalyzed rxn:

A

Enzyme inhibitor

69
Q

Give the types of inhibitors:

A

Competitive vs noncompetitive

Reversible vs irreversible

70
Q

The Km in competitive inhibition will inc or dec?

A

Increase

71
Q

Inhibitors bind to a different site from the active site:

A

Noncompetitive

Biochem Module 2 (1 decks)

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