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Biochem > Enzymes > Flashcards

Enzymes Flashcards

1
Q

Protein catalysts that increase the velocity of a chemical reaction and are not consumed during the reaction they catalyze

A

Enzymes

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2
Q

Physically distinct versions of a given enzyme, each of which catalyzes the same reaction

A

Isozymes

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3
Q

Catalyze oxidations and reductions

A

Oxidoreductases

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4
Q

Catalyze transfer of moieties such as glycosyl, methyl, or phosphoryl groups

A

Transferases

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5
Q

Catalyze hydrolytic cleavage of C-C, C-O, C-N and other bonds

A

Hydrolases

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6
Q

Catalyze cleavage of C-C, C-O, C-N and other bonds by atom elimination, leaving double bonds

A

Lyases

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7
Q

Catalyze geometric or structural changes within a molecule

A

Isomerases

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8
Q

Catalyze the joining together of two molecules coupled to the hydrolysis of ATP

A

Ligases

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9
Q

Properties of Enzymes

A

Contain an active siteHighly efficientHighly specificRequire cofactorsCompartmentalizedCan be regulated or inhibited

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10
Q

Distinguished by their tight, stable incorporation into protein’s structure by covalent or noncovalent forces

A

Prosthetic Group

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11
Q

Bind in transient, dissociable manner either to the enzyme or to a substrate

A

Cofactor

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12
Q

Serve as recyclable shuttles or group transfer agents that transport many substrates from their point of generation to their point of utilization

A

Coenzyme

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13
Q

How enzymes work?

A

Lower free energy of activationDo not change the energy of the reactants and products and the equilibrium of the reaction

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14
Q

Describes how reaction velocity varies with substrate concentration

A

Michaelis-Menten Equation

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15
Q

Enzymes that follow Michaelis-Menten Kinetics have a

A

Hyperbolic curve

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16
Q

Allosteric reactions have

A

Sigmoid curve

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17
Q

Low substrate affinity =

A

High Km

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18
Q

High substrate affinity =

A

Low Km

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19
Q

Factors that affect the reaction rate

A

Substrate concentrationTemperaturepH

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20
Q

Zero Order KineticsRate not affected by substrate concentration

A

Above Km

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21
Q

First Order KineticsRate directly proportional to substrate concentration

A

Below Km

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22
Q

High Temperature =

A

Increased reaction rate

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23
Q

Extremely High Temperature =

A

Decreased reaction rate (due to denaturation)

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24
Q

pH Extremes =

A

Decreased reaction rate (due to denaturation)

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25
Q

Reciprocal of the Michaelis-Menten Equation; Used to calculate Km and Vmax as well as to determine the mechanism of action of enzyme inhibitors

A

Lineweaver-Burk Plot

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26
Q

Any substance that can diminish the velocity of an enzyme-catalyzed reaction

A

Enzyme inhibitor

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27
Q

Inhibitor is shaped similar to substrate and competes for binding site; Increase substrate, Increased Km, Vmax Not changed

A

Competitive Inhibitor

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28
Q

Inhibitor binds to enzyme somewhere other than the active site and halts catalysis; Increased enzyme, Km Not changed, Vmax Lowered

A

Noncompetitive Inhibitor

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29
Q

Regulation of Enzyme Activity

A

Change in substrate concentrationThrough allosteric binding sitesThrough covalent modification of the enzymeThrough induction and repression of enzyme synthesis

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30
Q

The substrate itself serves as an effector

A

Homotropic Effectors

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31
Q

The effector is different from the substrate

A

Heterotropic Effectors

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32
Q

Serum Enzyme: Aspartate aminotransferase

A

Myocardial infarction

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33
Q

Serum Enzyme: Alanine aminotransferase

A

Viral hepatitis

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34
Q

Serum Enzyme: Amylase

A

Acute pancreatitis

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35
Q

Serum Enzyme: Ceruloplasmin

A

Hepatolenticular degeneration (Wilson’s disease)

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36
Q

Serum Enzyme: Creatine kinase

A

Muscle disorders and Myocardial infarction

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37
Q

Serum Enzyme: Gamma-Glutamyl transpeptidase

A

Various liver diseases

38
Q

Serum Enzyme: Lactate dehydrogenase (isozymes)

A

Myocardial infarction

39
Q

Serum Enzyme: Lipase

A

Acute pancreatitis

40
Q

Serum Enzyme: Phosphatase, acid

A

Metastatic carcinoma of the prostate

41
Q

Serum Enzyme: Phosphatase, alkaline (isozymes)

A

Various bone disorders, obstructive liver diseases

42
Q

Transfer and utilization of energy in biologic systems

A

Bioenergetics

43
Q

Measure of heat content of the reactants and products; Measure in joules

A

Enthalpy (

44
Q

Measure of the change in randomness or disorder of the reactants and products; Measured in joules/Kelvin

A

Entrophy (

45
Q

Amount of energy that can be used;

A

Change in Free Energy (

46
Q

(-) Enthalpy (+) Entropy =

A

Always Spontaneous Reaction

47
Q

(+) Enthalpy (-) Entropy =

A

Always No Spontaneous Reaction

48
Q

(+) Enthalpy (+) Entropy =

A

Maybe Spontaneous Reaction, but only at High Temp

49
Q

(-) Enthalpy (-) Entropy =

A

Maybe Spontaneous Reaction, but only at Low Temp

50
Q

Adenosine molecule to which three phosphate groups are attached; Acts as the “energy currency” of the cell, transferring free energy derived from substances of higher energy potential to those of lower energy potential

A

Adenosine Triphosphate

51
Q

Any

A

Used to make ATP

52
Q

Any

A

Made from ATP

53
Q

How ATP is produced?

A

Phosphate transferOxidative phosphorylation

54
Q

Sources of High Energy Phosphorylation

A

Oxidative PhosphorylationSubstrate Level Phosphorylation

55
Q

Aerobic; The greatest quantitative source of high energy phosphate in aerobic organisms; Free energy comes from successive oxidation of substances in the respiratory chain within mitochondria; Molecular oxygen is the final substance to be reduced

A

Oxidative Phosphorylation

56
Q

Anaerobic; Done through coupling reactions where a phosphate group is transferred to ADP from another substance with higher

A

Substrate Level Phosphorylation

57
Q

In Glycolysis: ATP is generated in 2 steps

A

1,3-BPG + ADP ➡️3-PG + ATP (phosphoglycerate kinase)PEP + ADP ➡️pyruvate + ATP (pyruvate kinase)

58
Q

In Citric Acid Cycle: ATP is generated in 1 step

A

Succinyl CoA + ADP➡️succinate + ATP (succinyl thiokinase)

59
Q

Final common pathway by which electrons from different fuels of the body flow to oxygen; Occurs in inner mitochondrial membrane

A

Electron Transport Chain

60
Q

2 electron carriers used in ETC:

A

Nicotinamide Adenine Dinucleotide (NAD+) - from Vit. B3 (Niacin)Flavin Adenine Dinucleotide (FAD) - from Vit. B2 (Riboflavin)

61
Q

Parts of ETC: Complex I

A

NADH dehydrogenase

62
Q

Parts of ETC: Complex II

A

Succinate dehydrogenase (actually part of Krebs Cycle)

63
Q

Parts of ETC: Coenzyme Q

A

A lipid, aka UbiquinoneOnly non-protein part of ETC

64
Q

Parts of ETC: Complex III

A

Cytochrome b/c1 (Fe/heme protein)

65
Q

Parts of ETC: Cytochrome C

A

Fe/Heme protein, mobile part of ETC

66
Q

Parts of ETC: Complex IV

A

Cytochrome a/a3 (Cu/heme protein) aka Cytochrome oxidase

67
Q

What you have to remember about ETC?

A

1) Protons (H+) are pumped to the intermembranous space to create a gradient in 3 complexes: Complex I-NADH and flavoprotein, Complex III-Cytochrome B & C, Cytochrome IV-Cytochrome C & a+a32) All components are fixed to the inner mitochondrial membrane EXCEPT Coenzyme Q/Ubiquinone, Cytochrome C3) Final electron acceptor is Oxygen

68
Q

From oxidation of components in the respiratory chain is coupled to the translocation of Hydrogen ions (protons/H+); H+ moved from the inside to the outside of the inner mitochondrial membrane where it accumulates in the intermembranous space

A

Mitchell’s Chemiosmotic Theory

69
Q

ETC generates an electrical gradient and a pH gradient across the inner mitochondrial membrane; Protons driven towards mitochondrial matrix; Results in the synthesis of ATP

A

Oxidative Phosphorylation

70
Q

2 components of ATP synthase

A

F1 - generates ATP from ADP + PiF2 - channel where protons pass through

71
Q

Deprives the ETC of sufficient oxygen, decreasing the rate of ETC and ATP production

A

Tissue Hypoxia

72
Q

Stops electron flow from substrate to oxygen

A

Inhibitors of ETC

73
Q

ETC Inhibitors: Complex I

A

BarbituratePiericidin AAmytalRotenone

74
Q

ETC Inhibitors: Complex II

A

MalonateCarboxinTTFA

75
Q

ETC Inhibitors: Complex III

A

Antimycin ADimercaprol

76
Q

ETC Inhibitors: Complex IV

A

CyanideCarbon monoxideSodium azideHydrogen sulfide

77
Q

Increase the permeability of the inner mitochondrial membrane to protons; Increased oxygen consumption; Increased oxidation of NADH; Decreased ATP synthesis

A

Uncouplers

78
Q

Examples of Synthetic Uncouplers

A

2,4 dinitrophenolAspirin

79
Q

Example of uncoupling proteins

A

Thermogenin

80
Q

Directly inhibits mitochondrial ATP Synthase (Complex V); Proton gradient continues to rise but there is no “escape valve” for the protons; ETC eventually stops because the cytochromes can no longer pump protons into the intermembranous space

A

ATP Synthase Inhibitors

81
Q

Example ATP Synthase Inhibitor

A

Oligomycin

82
Q

Reactive Oxygen Species

A

Superoxide (O2-)Hydrogen peroxide (H2O2)Hydroxyl radical (OH-)

83
Q

Unstable products that are formed as a by-product of ETC when molecular oxygen (O2) is partially reduced

A

Reactive Oxygen Species

84
Q

Mutation in the circular mitochondrial chromosome; Maternally inherited

A

Mitochondrial Diseases

85
Q

Mutation in the circular mitochondrial chromosome that encodes:

A

1) 13 proteins that comprise the major complexes of Oxidative Phosphorylation2) 22 tRNAs3) 2 rRNAs

86
Q

Examples of Mitochondrial Disease: All Complexes

A

Fatal Infantile Mitochondrial Myopathy

87
Q

Examples of Mitochondrial Disease: Complex I

A

MELAS (Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like episodes)

88
Q

Examples of Mitochondrial Disease: Complex II

A

Kearns-Sayre Syndrome

89
Q

Examples of Mitochondrial Disease: Complex III

A

Leber’s Hereditary Optic Neuropathy

90
Q

Examples of Mitochondrial Disease: Complex IV

A

Leigh’s DiseaseRagged Red Muscle Fiber Disease

Biochem (7 decks)

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