Enzymes

Question 1

Enzymes are proteins that ___ the rates of biochemical reactions; ___

Answer 1

increase, biological catalysts

Question 2

Enzymes make up ____ ____ such as those that synthesize new molecules and generate __ ____

Answer 2

metabolic pathways, cellular energy

Question 3

Three distinct features of enzymes

Answer 3

1. Catalytic power
2. Specificity
3. Regulation

Question 4

Increases the rates of biochemical reactions as much as 10^16

Answer 4

Catalytic power

Question 5

Selectively act upon a substrate to carry out a particular reaction

Answer 5

Specificity

Question 6

Enzyme activity is regulated by a variety of mechanisms

Answer 6

Regulation

Question 7

____ ____ increase the rates of biochemical reactions as much as __

Answer 7

catalytic power, 10^16

Question 8

_____ selectively act upon a ____ to carry out a ____ reaction

Answer 8

specificity, substrate, particular

Question 9

____ enzyme activity is regulated by a ___ of mechanisms

Answer 9

regulation, variety

Question 10

How many fundamental categories can enzymes be classified in?

Answer 10

6 fundamental categories

Question 11

Fundamental Enzyme Category:
Oxidoreductases

Answer 11

Transfer electrons from one molecule to another

Question 12

Fundamental Enzyme Category:
Transferases

Answer 12

Transfer chemical groups

Question 13

Fundamental Enzyme Category:
Hydrolases

Answer 13

Break covalent bonds by hydrolysis

Question 14

Fundamental Enzyme Category:
Lyases

Answer 14

Cleave various bonds, or add groups to double bonds

Question 15

Fundamental Enzyme Category:
Isomerases

Answer 15

Produce isomers

Question 16

Fundamental Enzyme Category:
Ligases

Answer 16

Join large molecules by forming covalent bonds

Question 17

Oxidoreductases ____ ____ from one molecule to another

Answer 17

transfer electrons

Question 18

Transferases transfer ___ ___

Answer 18

chemical groups

Question 19

Hydrolases break ____ ____ by hydrolysis

Answer 19

covalent bonds

Question 20

Lyases ____ various bonds, or ___ groups to ___ ____

Answer 20

cleave, add double bonds

Question 21

Isomerases _____ isomers

Answer 21

produce

Question 22

Ligases join ____ ____ by forming ___ ____

Answer 22

large molecules, covalent bonds

Question 23

Cofactors are ___ ___ or ___ ____ that bond to enzymes and are required for ___ ____

Answer 23

metal ions, organic molecules, enzyme activity

Question 24

Coenzymes are ___ ___ (B-vitamin derivatives) that act as ___ ____

Answer 24

organic molecules, enzyme cofactors

Question 25

Prosthetic groups are tightly bound ___ or ____

Answer 25

cofactors or coenzymes

Question 26

Holoenzyme are _____ ___ complex of ___ and _____

Answer 26

catalytically active, protein and coenzyme

Question 27

Apoenzyme are ___ without the ___ ___

Answer 27

proteins, prosthetic group

Question 28

Holoenzyme are made of ___ and ____

Answer 28

protein and coenzyme

Question 29

Coenzymes are ___ ___

Answer 29

organic molecules

Question 30

Cofactors are ___ or ____

Answer 30

metal ions or organic molecules

Question 31

Prosthetic groups are ____ or ____

Answer 31

cofactors or coenzymes

Question 32

Apoenzymes are ____

Answer 32

proteins

Question 33

Understanding the rates and processes of chemical reactions is ____

Answer 33

chemical kinetics

Question 34

velocity (v) or the ____ ___ ____, is the amount of ___ formed or the amount of __ consumed per unit of time

Answer 34

rate of the reaction, P, A

Question 35

The velocity (or rate) is ______ to the concentration of __

Answer 35

proportional, A

Question 36

What is the proportionality constant or rate constant?

Answer 36

k

Question 37

v=k[A] is the equation for what?

Answer 37

first order reaction

Question 38

The Michaelis-Menten Equations is a

Answer 38

kinetics of enzyme-catalyzed reaction

Question 39

v=k[A][B] is the equation for what?

Answer 39

second order reaction

Question 40

In a __ ___ ___, there is a directly proportionate relationship between substrate concentration and the amount of produce produced per unit time

Answer 40

first order reaction

Question 41

The Michaelis-Menton equation __ is no longer dependent on __ and the equation is obeying __ __ __

Answer 41

v, [S], zero-order kinetics

Question 42

The Michaelis-Menton equation is __ ___ ____

Answer 42

zero order reaction

Question 43

What equation is used for the kinetics of enzyme catalyzed reactions?

Answer 43

Michaelis-Menton equation

Question 44

The M/M equation gives the rate of an enzyme reaction (v) in terms of what?

Answer 44

substrate concentration

Question 45

What are the two constants in the M/M equation?

Answer 45

Vmax, Km

Question 46

When substrate concentration is high, v=_____

Answer 46

v=Vmax

Question 47

When substrate concentration is high, v is no longer dependent on what?

Answer 47

substrate concentration

Question 48

When substrate concentration is high, the reaction is following what order kinetics?

Answer 48

zero

Question 49

When substrate concentration is low, the reaction is following what order kinetics?

Answer 49

first

Question 50

What variables are fixed in the M/M equation?

Answer 50

temp, pH, and ionic strength

Question 51

v=(vmax/Km)*[S] is the equation for when the substrate concentration is __

Answer 51

low (first order)

Question 52

The M/M equation for an enzyme-catalyzed reaction describes a ___ ___

Answer 52

hyperbolic curve

Question 53

What is the shape of the curve of the M/M equation?

Answer 53

hyperbolic curve

Question 54

A __ __ is a curve that approaches but never reaches the max value

Answer 54

hyperbolic curve

Question 55

v=

Answer 55

product produced/unit time

Question 56

Km is the ___ ___ at which the rate of the reaction, v, is ___ ____ since v=1/2Vmax when [S]=Km

Answer 56

substrate concentration, half maximal

Question 57

At Vmax/2, what is equal to what?

Answer 57

substrate, enzyme

Question 58

Km is a measure of what?

Answer 58

amount of substrate/unit volume

Question 59

Kcat is the value for what?

Answer 59

catalytic constant/turnover number

Question 60

Kcat measures the __ amount of product produced per second when the enzyme is ___ with the substrate

Answer 60

maximum, saturated

Question 61

Kcat ___ greatly for different enzymes

Answer 61

varies

Question 62

What is the pH that most enzymes have peak activity?

Answer 62

7.4

Question 63

Kcat must be determined and compared under what type of conditions?

Answer 63

the same

Question 64

Kcat is similar to what other value?

Answer 64

Vmax of the M/M equation

Question 65

Kcat is determined under ___, standard conditions

Answer 65

fixed

Question 66

The activity most enzymes have a peak at around __

Answer 66

40 degrees C

Question 67

Kcat values are high/low because of what two things?

Answer 67

1. efficiency of the enzyme 2. nature of substrate (large, complex vs small, simple)

Question 68

Staphylococcal nuclease has a __ Kcat

Answer 68

low (95)

Question 69

Carbonic anhydrase has a __ Kcat

Answer 69

high (1,000,000)

Question 70

[S] large =

Answer 70

zero order kinetics

Question 71

[s] very small =

Answer 71

first order kinetics

Question 72

What does enzyme staphylococcal nuclease do?

Answer 72

attack DNA, RNA, and other molecules

Question 73

Why does carbonic anhydrase have such a high kcat?

Answer 73

CO2 and H2O are simple and small molcules

Question 74

There's no activity at too low or too high of pH because of the interaction of what part of the amino acid?

Answer 74

positively or negatively charged side chains

Question 75

___ is an enzyme that breaks down food in the stomach, and is therefore at peak activity at a ___ pH of ___

Answer 75

pepsin, low, 1.5

Question 76

___ is an enzyme that breaks down food in the intestines and has peak activity at pH 7.7

Answer 76

trypsin, 7.7

Question 77

What in the stomach makes it acidic?

Answer 77

HCl

Question 78

At low temps, enzyme activity is ___ due to lack of energy

Answer 78

slowed

Question 79

At high temps, enzyme activity might undergo irreversible ____

Answer 79

denaturing (unfolding)

Question 80

denaturing of enzymes causes lack of ___

Answer 80

activity

Question 81

What are the two reversible enzyme inhibitors?

Answer 81

1. Competitive Inhibitors 2. Noncompetitive inhibitors

Question 82

Competitive inhibitors are _____ _____ ____

Answer 82

reversible enzyme inhibitors

Question 83

Noncompetitive inhibitors are ___ ____ ___

Answer 83

reversible enzyme inhibitors

Question 84

the ____ and _____ bind to the same site (the active site) on the enzyme in a ____ ____

Answer 84

substrate (S) and inhibitor (I), competitive inhibitor

Question 85

the inhibitor binds to a site different from the active site and brings about a _____ ____ that _____ enzyme activity in a _______ _____

Answer 85

conformational change, reduces, noncompetitive inhibitor

Question 86

What are the two types of noncompetitive inhibitors?

Answer 86

Mixed & pure

Question 87

Mixed inhibitors ____ kcat and ___ substrate binding (Km)

Answer 87

decrease, change

Question 88

Pure inhibitors are _____

Answer 88

uncommon

Question 89

Pure inhibitors _____ kcat, but ____ affect substrate binding (Km)

Answer 89

decrease, don't

Question 90

A competitive inhibitor is similar in ___ and __ to the normal substrate.

Answer 90

size, shape

Question 91

A competitive inhibitor cannot undergo a ___ ____

Answer 91

chemical reaction

Question 92

The inhibitor and substrate compete for a binding site to the active site of the enzyme in ___ ___

Answer 92

competitive inhibition

Question 93

The inhibitor and substrate bind to different sites in __ ____

Answer 93

noncompetitive inhibition

Question 94

Binding of the inhibitor ____ the activity of the enzyme and therefore decreases Kcat and Vmax in noncompetitive inhibition

Answer 94

decreases

Question 95

Inhibitors might make it so the substrate is ___ bound to the enzyme.

Answer 95

loosely

Question 96

Inhibitors decrease the ____ of the subsrate/reaction

Answer 96

Vmax

Question 97

Inhibitos increase ____ of the substrate/reaction

Answer 97

Km

Question 98

Irreversible inhibitors binds ____ to the enzyme, usually by ___ ___

Answer 98

irreversibly, covalent bonds

Question 99

____ substrates generate a reactive group that forms a covalent bond during binding the active site.

Answer 99

suicide

Question 100

Penicillin is an example of ___ substrate

Answer 100

suicide

Question 101

Penicillin forms a covalent bond with an enzyme involved in the synthesis of what?

Answer 101

bacterial cell walls.