Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Vitamins and Enzymes > Enzymes > Flashcards

Enzymes Flashcards

1
Q

Define enzyme

A

Enzymes are proteins that act as catalysts for biochemical reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

True or false: enzymes are consumed in the reaction

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

True or false: enzymes are the most effective catalysts

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Enzymes are usually what kind of protein?

A

Globular proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

True or false: enzymes undergo all the reactions of proteins including denaturation

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Name three things enzyme activity is effected by

A

Temperature, alterations in pH, and other protein denaturants like microwaves, heavy metals etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

*Enzyme inhibitor

A

Drugs and compounds that modify drug action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Name the two types of enzymes

A

Simple and conjugated enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

*Simple enzyme

A

Composed only of protein (amino acid chains)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

*Conjugated enzyme

A

Has a non-protein part in addition to a protein part

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

*Apoenzyme

A

Protein part of a conjugated enzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

*Holoenzyme

A

The biochemically active conjugated enzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

*Apoenzyme+cofactor =

A

Holoenzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

*Cofactor

A

Non-protein part of a conjugated enzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

*Substrate

A

Reactant in an enzyme catalyzed reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Cofactors are important

A

for the chemically reactive enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a cofactor

A

Cofactors are small organic molecules or Inorganic ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Organic molecule cofactors

A

also called co-enzymes or co- substrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Co-enzymes/co-substrates are derived from

A

dietary vitamins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Inorganic ion cofactors

A

Typical metal ion cofactors - Zn2+, Mg2+, Mn2+, and Fe2+
• Nonmetallic ion cofactor - Cl-
• Inorganic ion cofactors derived from dietary minerals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Role of iron cofactor

A

oxidation/reduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Role of copper cofactor

A

oxidation/reduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Role of zinc cofactor

A

Helps bind NAD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Role of biotin coenzyme

A

carries COO-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Role of coenzyme A

A

carries CH2-CH3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Role of NAD coenzyme

A

carries electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Role of FAD coenzyme

A

carries electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Role of heme

A

Binds ions, O2, and electrons; contains iron cofactor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Role of Flavin

A

binds electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Role of Retinal

A

converts light energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Nomenclature of enzymes

A

Most commonly named with reference to their function
– Type of reaction catalyzed
– Identity of the substrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

*substrate

A

the reactant in an enzyme-catalyzed reaction:
– The substrate is the substance upon which the enzyme “acts.”
– E. g., In the fermentation process, sugar is converted to alcohol, therefore in this reaction sugar is the substrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

-ase

A

identifies it as an enzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

-in

A

can also identify an enzyme ex: pepsin, trypsin, chymotrypsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Oxidase

A

catalyzes an oxidation reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Hydrolase

A

catalyzes a hydrolysis reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Predict the function of the following enzymes.

a. Maltase
b. Lactate dehydrogenase
c. Fructose oxidase
d. Maleate isomerase

A

a. Hydrolysis of maltose;
b. Removal of hydrogen from lactate ion;
c. Oxidation of fructose;
d. Rearrangement (isomerization) of maleate ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Name the six major classes on enzymes

A
  1. Oxidoreductases
  2. Transferases
  3. Hydrolases
  4. Lyases
  5. Isomerase
  6. Ligases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Oxidoreductases

A

Oxidation-reductions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Transferases

A

an enzyme that catalyzes the transfer of a functional group from one molecule to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Hydrolases

A

Hydrolysis reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Lyases

A

Reactions involving addition or removal of groups form double bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Isomerase

A

Isomerization reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Ligases

A

Reactions involving bond formation coupled with ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

True or false: Oxidation and reduction reactions are always linked to one another

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

An oxidoreductase requires

A

a coenzyme that is either oxidized or reduced as the substrate in the reaction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

The two major subtypes of transferases

A

Transaminases and Kinases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Transaminases

A

catalyze transfer of an amino group to a substrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Kinases

A

catalyze transfer of a phosphate group from adenosine triphosphate (ATP) to a substrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Kinase inhibitors

A

Newer drug classes for treating cancer, inflammation

51
Q

A hydrolase reaction involves

A

the addition of a water molecule to a bond to cause bond breakage

52
Q

Carbohydrases

A

catalyze the hydrolysis of glycosidic bonds in oligo- and polysaccharides

53
Q

Proteases

A

catalyze the hydrolysis of peptide bonds in proteins

54
Q

Esterases

A

catalyze the hydrolysis of peptide bonds in proteins

55
Q

Lipases

A

catalyze the hydrolysis of ester bonds in triacylglycerols

56
Q

Dehydratase

A

effects the removal of the components of water from a double bond

57
Q

Hydratase

A

effects the addition of the components of water to a double bonds

58
Q

A ligase requires =

A

ATP hydrolysis because such reactions are energetically unfavorable and simultaneous input of energy obtained by a hydrolysis of ATP to ADP

59
Q

*The active site

A

Relatively small part of an enzyme’s structure that is actually involved in catalysis

60
Q

*Functions of the active site

A

Place where substrate binds to enzyme
– Formed due to folding and bending of the protein.
– Usually a “crevice like” location in the enzyme
– Some enzymes have more than one active site

61
Q

*Lock-and-Key model

A

Enzyme has a pre-determined shape for the active
site
– Only substrate of specific shape can bind with active site

62
Q

*Induced Fit Model

A

Substrate contact with enzyme will change the shape
of the active site
– Allows small change in space to accommodate substrate (e.g., how a hand fits into a glove)

63
Q

Forces That Determine Substrate Binding

A
  • H-bonding
  • Hydrophobic interactions
  • Electrostatic interactions – salt bridge
64
Q

*Absolute Specificity

A

An enzyme will catalyze a particular reaction for only one substrate
– This is most restrictive of all specificities (not common)

65
Q

*Stereochemical Specificity

A

An enzyme can distinguish between stereoisomers
– Chirality is inherent in an active site (amino acids are chiral compounds)
– L-Amino-acid oxidase - catalyzes reactions of L-amino acids but not of D-amino acids.

66
Q

*Group Specificity

A

nvolves structurally similar compounds that have the same functional groups.

67
Q

*Linkage Specificity

A

– Involves a particular type of bond irrespective of the structural features in the vicinity of the bond
– Considered most general of enzyme specificities

68
Q

Phosphatases

A

Hydrolyze phosphate–ester bonds in all

types of phosphate esters

69
Q

Enzyme Activity

A

A measure of the rate at which enzyme converts substrate to products in a biochemical reaction

70
Q

*Four factors affect enzyme activity:

A

– Temperature
– pH
– Substrate concentration
– Enzyme concentration

71
Q

*The effect of temperature on an enzyme

A

Higher temperature results in higher kinetic energy which causes an increase in number of reactant collisions, therefore there is higher activity.

72
Q

Optimum temperature

A

Temperature at which the rate of enzyme catalyzed reaction is maximum

73
Q

Optimum temperature for human enzymes

A

37oC (body temperature)

74
Q

*Increased temperature (high fever) leads to

A

decreased enzyme activity

75
Q

*Drastic changes in pH can result in

A

denaturation of proteins

76
Q

*Optimum pH:

A

pH at which enzyme has maximum activity

77
Q

Most enzymes have optimal activity in the pH range of

A

7.0 - 7.5

78
Q

Pepsin: Optimum pH =

A

1.5 – 1.6

79
Q

Trypsin: Optimum pH =

A

7.8 – 8.7

80
Q

*Effect of substrate concentration on an enzyme

A

At a constant enzyme concentration, the enzyme activity increases with increased substrate concentration

81
Q

Substrate saturation:

A

the concentration at which it reaches its maximum rate and all of the active sites are full

82
Q

Turnover Number:

A

Number of substrate molecules converted to product per second per enzyme molecule under conditions of optimum temperature and pH

83
Q

True or False: Enzymes are not consumed in the reactions they catalyze

A

True

84
Q

*Effects of enzyme concentration

A

At a constant substrate concentration, enzyme activity increases with increase in enzyme concentration

85
Q

*The greater the enzyme concentration..

A

the greater the reaction rate.

86
Q
  • Describe the effect that each of the following changes would have on the rate of a reaction that involves the substrate sucrose and the intestinal enzyme sucrase.
    a. Decreasing the sucrase concentration
    b. Increasing the sucrose concentration
    c. Lowering the temperature to 10oC
    d. Raising the pH from 6.0 to 8.0 when the optimum pH is 6.2
A

a. Decrease rate b. Increase rate c. Decrease rate d. Decrease rate

87
Q

*Extremeophiles

A

Organisms that thrive in extreme environments.

88
Q

Hydrothermophiles

A

Thrive at 80o-122oC and high pressure.

89
Q

Acidophiles

A

Optimal growth pH

90
Q

Alkaliphiles

A

Optimal growth pH >9.0

91
Q

Halophiles

A

Live in highly saline conditions (>0.2 M NaCl).

92
Q

Piezophiles

A

Grow under high hydrostatic pressure

93
Q

Cryophiles

A

Grow at temps

94
Q

*Extremozyme

A

A microbial enzyme that is active at conditions that would inactivate human enzymes as well as enzymes present in most other organisms.

95
Q

*Extremozymes are of high interest for industrial chemists…

A

Enzymes are heavily used in industrial processes

– Industrial processes require extremes of temp, pressure, and pH.

96
Q

*Extremozyme Applications

A
  • Biotechnology industry – Production of enzymes for industrial applications.
  • Petroleum industry – Oil well drilling operations – degumming of guar gum.
  • Environmental scavenging and removal of heavy metals
  • Environmental clean-up using genetically engineered extremophiles.
  • Laundry detergents used in cold wash cycles
97
Q

Enzyme Inhibitor

A

a substance that slows down or stops the normal catalytic function of an enzyme by binding to it

98
Q

Two type of enzyme inhibitors

A

Competitive and Noncompetitive Inhibitors

99
Q

*Competitive Inhibitors

A

Compete with the substrate for the same active site

• Will have similar charge & shape

100
Q

Noncompetitive Inhibitors:

A

Do not compete with the substrate for the same active site

• Binds to the enzyme at a location other than active site

101
Q

Reversible Competitive Inhibition

A

A competitive enzyme inhibitor decreases enzyme activity by binding to the same active site as the substrate.
• Binds reversibly to an enzyme active site and the inhibitor remains unchanged (no reaction occurs)
• The enzyme - inhibitor complex formation is via weak interactions (hydrogen bonds, etc.).
• Competitive inhibition can be reduced by simply increasing the concentration of the substrate.

102
Q

Reversible Noncompetitive Inhibition

A
  • A noncompetitive enzyme inhibitor decreases enzyme activity by binding to a site on an enzyme other than the active site.
  • Causes a change in the structure of the enzyme and prevents enzyme activity.
  • Increasing the concentration of substrate does not completely overcome inhibition.
  • Examples: Heavy metal ions Pb2+, Ag+, and Hg2+.
103
Q

*Irreversible Inhibition

A

An irreversible enzyme inhibitor inactivates enzymes by forming a strong covalent bond with the enzyme’s active site.
– The structure is not similar to enzyme’s normal substrate
– The inhibitor bonds strongly and increasing substrate concentration does not reverse the inhibition process
– Enzyme is permanently inactivated.
– E.g., Chemical warfare agents (nerve gases) and organophosphate insecticides

104
Q

Nerve gas Sarin:

A

Irreversible inhibitor of AChE causes muscular paralysis, convulsions, bronchial constriction, and death by asphyxiation

105
Q

True or false: Cellular processes continually produces large amounts of an enzyme and plentiful amounts of products if the processes are not regulated

A

True

106
Q

General mechanisms involved in regulation:

A

– Proteolytic enzymes and zymogens
– Covalent modification of enzymes
– Feedback control Regulation of enzyme activity by various substances produced within a cell
• The enzymes regulated are allosteric enzymes

107
Q

*Properties of Allosteric Enzymes

A

• All allosteric enzymes have quaternary structure: – Composed of two or more protein chains
• Have at least two of binding sites:
– Substrate and regulator binding site
• Active and regulatory binding sites are distinct from each other:
– Located independent of each other
– Shapes of the sites (electronic geometry) are different

108
Q

Binding of molecules at the regulatory site causes changes in the overall three dimensional structure of the enzyme:

A

– Change in three dimensional structure of the enzyme leads to change in enzyme activity
– Some regulators increase enzyme activity – activators
– Some regulators decrease enzyme activity - inhibitors

109
Q

*Feedback Control:

A

A process in which activation or inhibition of the first reaction in a reaction sequence is controlled by a product of the reaction sequence

110
Q

Regulators of a particular allosteric enzyme may be:

A

– Products of entirely different pathways of reaction within the cell
– Compounds produced outside the cell (hormones)

111
Q

Feedback Control

A

Enzyme 1 inhibited by product D
A—–> B —-> C —-> D
Enz 1 Enz 2 Enz 3

112
Q

*Proteolytic Enzymes and Zymogens

A

Mechanism of regulation by production of enzymes in inactive forms (zymogens).
• Zymogens, also known as pro-enzymes, are “turned on” at the appropriate time and place
– Example: proteolytic enzymes: Most digestive and blood-clotting enzymes are proteolytic enzymes
– Hydrolyze peptide bonds in proteins

113
Q

*Covalent modification

A

A process in which enzyme activity is altered by covalently modifying the structure of the enzyme
– Involves adding or removing a group from an enzyme

114
Q

*Most common covalent modification - addition and removal of phosphate group:

A

Phosphate group is often derived from an ATP molecule.
– Addition of the phosphate (phosphorylation) catalyzed by a Kinase enzyme
– Removal of the phosphate group (dephosphorylation) catalyzed by a phosphatase enzyme.
– Phosphate group is added to (or removed from) the R group of a serine, tyrosine, or threonine amino acid residue in the enzyme regulated.

115
Q

*• Many common prescription drugs exert their mode of action by inhibiting enzymes
• Examples:

A

Penicillins, Kinase inhibitors, Solvaldi, Harvoni

116
Q

*Sulfa drugs

Antibiotic:

A

A substance that kills bacteria or inhibits its growth

117
Q

*Kinase inhibitors

A

–Tyrosine Kinase Inhibitors (TKIs)
• Many on market, under development
• Ex: Gleevec, BCR-ABL inhibitor for treating chronic myelogenous leukemia (CML)

118
Q

*Solvaldi, Harvoni

A

Hepatitis C virus NS5B inhibitors

119
Q

Penicillins all have structures..

A

containing a four-membered Beta- lactam ring fused with a five-membered thiazolidine ring

120
Q

*Penicillin selectively inhibits ..

A

bacterial transpeptidase by covalent modification of serine residue

121
Q

Transpeptidase catalyzes the formation

A

of peptide cross links between polysaccharides strands in bacterial cell walls

122
Q

*Grapefruit Juice is an

A

Enzyme Inhibitor which inhibits Cytochrome P450
(CYP) enzymes present in the liver. This can have
an impact on drugs which are supposed to be metabolized causing higher drug concentrations and toxicity.

123
Q

*enzyme-substrate complex

A

the intermediate reaction species that is formed when a substrate binds to the active site of an enzyme

124
Q

*ACE Inhibitor
stands for
function

A

angiotensin-converting enzyme, octapeptide hormone

used to treat high blood pressure conditions as well as several heart conditions,

Vitamins and Enzymes (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions