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ENZYMES > ENZYMES > Flashcards

ENZYMES Flashcards

1
Q

Proteins that act as catalysts for biochemical reactions, increasing the rate of reaction by lowering the energy of activation without being consumed in the process.

A

Enzymes

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2
Q

The first identified enzyme that converted starch to sugar

A

Diastase

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3
Q

modulates an enzyme activity

A

Effectors

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4
Q

are found in animal and plant cells. It is needed to speed up the breakdown of hydrogen peroxide and breaks it down to oxygen and water.

A

Catalase

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5
Q

Synthesizes starch by combining multiple glucose-1-phosphate molecules

A

Potato phosphorylase

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6
Q

It allows enzymes to significantly accelerate biochemical reactions, making them 10^3 to 10^17 times faster than uncatalyzed reactions

A

Catalytic Efficiency

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7
Q

The ability of an enzyme to interact with one or a few specific substrates and catalyze only one type of chemical reaction

A

Specificity

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8
Q

Mild reaction conditions

A

37℃, physiological pH, ambient atmospheric pressure.

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9
Q

Part of the enzyme where the reactants bind and where the biochemical reaction occurs

A

Active site

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10
Q

The enzyme active site is usually composed of :

A

amino acid side chains interact, metal ions, various types of polar, non-polar, ionic interactions

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11
Q

Found in saliva and the pancreas, breaks down starch into maltose.

A

Amylase

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12
Q

The active site is a region within an enzyme that fits the shape of molecules called ___

A

substrates/reactants.

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13
Q

Describes how substrates fit into the active site of an enzyme

A

The ‘Lock and Key Model’

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14
Q

Additional non-protein molecules needed by some enzymes to help the reaction

A

Cofactors

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15
Q

anything that is covalently bonded to an enzyme

A

Prosthetic group

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16
Q

apoenzyme and the nonprotein part

A

Holoenzyme

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17
Q

present in trace amounts within the enzyme.

A

Metal ions

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18
Q

Zn 2+ a cofactor for

A

carboxypeptidase

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19
Q

non-protein or organic, maybe a vitamin

A

Coenzyme

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20
Q

Enzymes that catalyze the same reaction in different tissues of the body.

A

Isoenzymes

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21
Q

converts lactate to pyruvate consists of five isoenzymes.

A

Lactate Dehydrogenase

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22
Q

have slight variations in the amino acid sequences of the subunits of their quaternary structure.

A

Isoenzymes

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23
Q

developed the four-integer number system and a name

A

Enzyme Commission

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24
Q

six major classes of enzyme-catalyzed reactions

A

Oxidoreductases
Transferases
Hydrolases
Lyases
Isomerases
Ligases.

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25
Q

Enhances reaction rates by holding two molecules in close proximity to each other

A

Facilitation of Proximity

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26
Q

Involves the transient covalent bonding of the substrate to an amino acid residue in the active site

A

Covalent Catalysis

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27
Q

This mechanism involves the transient covalent bonding of the _____ to an amino acid residue in the__& . Generally, this is to the ____ group of a serine, although the side chains of ____, ____,____ ,____ , and ____can also be involved.

A

Substrate, active site, hydroxyl,threonine, cysteine, histidine, arginine, lysine

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28
Q

Amino acid residues act as weak acids or weak bases, stabilizing normally unstable charge intermediates.

A

General Acid-Base Catalysis

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29
Q

An enzyme that catalyzes the oxidation of alcohols

A

Alcohol Dehydrogenase

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30
Q

weak acids
weak bases

A

proton donors
proton acceptors

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31
Q

Accounts for the lowering of activation energy for a reaction

A

Binding Energy

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32
Q

A metal-substrate-enzyme complex can aid in the orientation of the substrate in the active site

A

Metal ions catalysis

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33
Q

Binding of the substrate distorts it in a way that facilitates the chemical reaction

A

Strain, Molecular Distortion, and Shape Change

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34
Q

Enzyme activity in body fluids reflects ___ status.

A

organ

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35
Q

Enzymes whose levels can increase following a heart attack

A

Creatine kinase

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36
Q

Increased enzyme synthesis can be ____ and release in serum correlates with degree of stimulation

A

induced

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37
Q

reflects the presence of inhibitors and activators

A

Enzyme Activity

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38
Q

Liver status marker

A

Alkaline phosphatase

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39
Q

Enzymes decreases in the presence of an inhibitor

A

Activity of serum

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40
Q

can be altered genetically

A

Enzyme activity

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41
Q

can alter its substrate affinity, co-factor binding stability, can be used as a diagnostic in comparison with normal enzyme

A

Mutation

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42
Q

identify specific messenger RNA or DNA sequences are replacing many traditional enzymatic based markers of genetic disease

A

PCR techniques

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43
Q

Measures levels of certain enzymes in blood or urine to assess how well the body’s systems are functioning

A

Enzyme test

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44
Q

Name some common enzymes used for clinical diagnosis.

A

Alanine aminotransferase (ALT), alkaline phosphatase, amylase, aspartate aminotransferase, creatine kinase, and lactate dehydrogenase.

45
Q

Initial input of energy required for a chemical reaction to occur

A

Activation energy

46
Q

Where the reaction is in between the reactant consumption and product formation

A

Transition state

47
Q

____ systems are very sensitive to temperature changes

A

Biological

48
Q

Enzyme controlled reactions proceed __ to ___ times faster than corresponding non-enzymic reactions

A

10^8 to 10^11

49
Q

Catalyze one type of reaction for a single substrate

A

Absolute enzymes

50
Q

for similar substrates

A

Group enzymes

51
Q

for a specific type of bond

A

Linkage enzymes

52
Q

States that the enzyme changes shape with the substrate, active site is not rigid.

A

Induced fit theory

53
Q

Explains enzyme specificity and the loss of activity when enzymes denature

A

Lock and Key hypothesis

54
Q

Suggests that the active site of an enzyme is flexible and adjusts its shape to fit the substrate

A

Induced fit model

55
Q

Catalyzes the hydrolysis of peptide bonds

A

Chymotrypsin

56
Q

reaction for the sucrase-catalyzed hydrolysis of sucrose

A

Sucrase + Sucrose → ES complex (reversible) → Sucrase + Glucose + Fructose (irreversible).

57
Q

Defined as the moles of substrate converted to product per unit time

A

Enzyme activity

58
Q

Steps of an enzymatic reaction

A
  1. Substrate approaches the active site.
  2. Enzyme-substrate complex forms.
  3. Substrate is transformed into products.
  4. Products are released.
  5. Enzyme is recycled.
59
Q

key points of the induced fit hypothesis

A
  1. Some proteins can change their shape.
  2. A substrate induces a change in the enzyme’s conformation.
  3. The active site is molded into a precise conformation
60
Q

Test the absorbance

A

spectrophotometer

61
Q

The rate of appearance of ___ or the rate of ____ of substrate.

A

product, disappearance

62
Q

Factors affecting enzyme activity

A
  1. Concentration of substrate
  2. Concentration of enzyme
  3. Temperature
  4. pH
  5. Activators
  6. Inhibitors
63
Q

proportional to the substrate concentration

A

increase in velocity

64
Q

Faster reaction but it reaches a ____ point when all the enzyme molecules are occupied.

A

saturation

65
Q

occurs when the enzyme is saturated

A

Maximum activity

66
Q

Enzymes are most active at

A

optimum temperature

67
Q

greatest number of collisions between enzyme and substrate.

A

optimum temperature

68
Q

denatures the protein

A

Raise temperature

69
Q

the increase in reaction rate with a 10 degrees Celsius rise in temperature.

A

Q10

70
Q

pH optimum for pepsin and trypsin

A

Pepsin has an optimum pH of 3 in the stomach, while trypsin has an optimum pH of 8 in the small intestines.

71
Q

optimum temperature for most enzymes outside the human body

A

30 degrees Celsius

72
Q

typical pH range for most enzymes

A

6 to 8

73
Q

Can lead to denaturation of an enzyme if the ionization state of amino acids critical to correct folding are altered

A

Extreme of pH

74
Q

optimum pH for some enzymes in the body

A

7.4

75
Q

Molecules that bind to enzymes and increase their activity.

A

Enzyme activators

76
Q

Molecules called effectors (modifiers) that bind noncovalently at a site other than the active site.

A

Allosteric Binding Sites

77
Q

addition or removal of phosphate groups to serine, threonine, or tyrosine residues

A

Covalent modification

78
Q

Many enzymes are localized in specific organelles, which helps in the regulation of the metabolic pathway

A

Location within the cell

79
Q

An inactive precursor of an enzyme that is activated by proteolysis.

A

Zymogen

80
Q

cells can also regulate the number of enzymes present by altering the rate of enzyme synthesis.

A

Induction and repression of enzyme synthesis

81
Q

chemicals that reduce the rate of enzymic reactions, usually working at low concentrations and blocking the enzyme without destroying it

A

Inhibitors

82
Q

is the substrate concentration at which the rate of the reaction is half-maximal, indicating the enzyme’s affinity for the substrate

A

Michaelis constant

83
Q

Can be assayed by the disappearance of substrate, appearance of product, continuous assay, and end point assay

A

Enzyme activity

84
Q

an enzyme-catalyzed reaction is dependent upon the substrate concentration

A

velocity (V)

85
Q

At the start of the reaction, it is first order with respect to substrate concentration, and at the end, it is zero order with respect to substrate concentration.

A

order of reaction change

86
Q

describes the kinetic behavior of many enzymes, relating reaction rate to substrate concentration

A

Michaelis-Menten equation

87
Q

The rate of reaction is ____ on substrate concentration.

A

dependent

88
Q

Kinetics of simple enzyme-catalyzed reactions

A

Saturation Kinetics

89
Q

are based on data from batch reactors with constant liquid volume where initial substrate and enzyme concentrations are known

A

Langmuir-Hinshelwood Kinetics

90
Q

are often just above the substrate concentration in a cell, and rates of reaction are sensitive to small changes in cellular substrate concentrations

A

Km values

91
Q

can be obtained from simple reaction scheme that involves a reversible step for enzyme-substrate complex formation and a dissociation step from the ES complex.

A

Saturation kinetics

92
Q

The maximum forward velocity of the reaction changes if more enzyme is added, but the addition of more substrate has no influence on it

A

rapid-equilibrium approach

93
Q

is used to determine rate parameters for Michaelis-Menten kinetics

A

Lineweaver-Burk

94
Q

represents the relationship between substrate concentration [S] and the rate of reaction v, allowing for the determination of Km and Vmax

A

Hanes - Woolf Plot

95
Q

Enzyme lose its catalytic activity due to the alteration of its three-dimensional shape

A

denatured

96
Q

during purification can occur due to pH extremes or temperature changes

A

Enzyme denaturation

97
Q

The binding of one substrate to the enzyme facilitates binding of other substrate molecules

A

Allosteric enzymes

98
Q

certain compounds may bind to enzymes and reduce their activity

A

Inhibited enzyme kinetics

99
Q

form a stable complex with the enzyme and reduce enzyme activity

A

Irreversible inhibitors

100
Q

may dissociate more easily from the enzyme after binding

A

Reversible inhibitors

101
Q

are usually substrate analogs and compete with the substrate for the active site of the enzyme

A

Competitive inhibitors

102
Q

are not substrate analogs; they bind on sites other than the active site and reduce enzyme affinity to substrate

A

Noncompetitive inhibitors

103
Q

bind to the ES complex only and have no affinity for the enzyme itself

A

Uncompetitive inhibitors

104
Q

can be overcome by high concentrations of substrate.

A

Competitive inhibition

105
Q

an increased value of the denominator without substrate concentration, leading to a reduced reaction rate

A

net effect of competitive inhibition

106
Q

high substrate concentrations may cause inhibition in some enzymatic reactions.

A

Substrate inhibition

107
Q

_____ of the pH optimum of enzymes requires a knowledge of the active site characteristics of enzymes, which are very difficult to obtain.

A

Theoretical prediction

108
Q

may affect the maximum reaction rate, the constant, and the stability of the enzyme

A

Changes in pH

ENZYMES (4 decks)

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