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biochemistry > chapter 13 > Flashcards

chapter 13 Flashcards

1
Q

How do enzymes differ from ordinary catalysts?

A

1) Higher reaction rates
2) Milder reaction conditions
3) Greater reaction conditions
4) Capacity for control

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2
Q

How are the reaction rates of enzymes different from uncatalyzed reactions and ordinary catalyzed reactions?

A

enzyme catalyst are typically 10^6 to 10^12 greaterthan uncatalyzed reactions and at least several orders greater than chemically catalyzed reactions

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3
Q

How do the conditions of enzyme catalyst and chemical catalyse differ?

A

Enzymatically catalyzed reactions occur under realitively milder conditions: temperature below 100 degrees C, atmospheric pressure and nearly neutral pH’s. In contrast, chemical catalysis often require elevated temperatures and pressures as well as extremes of pH.

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4
Q

How does reaction specificity differ between enzyme catalyze reactions and chemical catalyze?

A

Greater specificity of enzyme catalyze reactions with respect to the identities of both substrates (reactants) and their products than chemical catalyst. That is enzymatic reactions rarley have side products

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5
Q

Why does the catalytic activities of many enzymes vary?

A

varies in response to concentration of substances other than their substrate and products.

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6
Q

What are the mechanisms that control the capacity of enzymes?

A

allosteric control

covalent modification of enzymes

and variation in amount of enzymes synthesized

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7
Q

enzymology

A

study of enzymes

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8
Q

diastase contains _____ and catalyzes what?

A

alpha amylase and catalyzes the hydrolysis of starch more efficiently sulfuric acid.

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9
Q

Lock and key hypothesis

A

The specificity of an enzyme (the lock) for its substrate (the key) arises from their geometrically complementary shapes.

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10
Q

what was the first enzyme catalyzed? which does what

A

Jack bean urease which catalyzes the hydrolysis of urea to NH3 and CO2

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11
Q

Enzymes are what types of molecule?

A

proteins

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12
Q

The noncovalent forces through which substrates and other molecules bind to enzymes are similar in character to what?

A

the forces that dictate the conformations of the proteins themselves: both involve van der Waals, electrostatic, hydrogen bonding and hydrophobic interaction.

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13
Q

In general a substrate binding site consists of what?

A

an indention or cleft on the surface of an enzyme molecule that is complementary in shape to the substrate (geometrically complementary)

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14
Q

Molecules that are different in shape or functional group distribution from the substrate do what?

A

do not bind to the enzyme; cannot form enzyme-substrate complexes that lead to the formation of products

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15
Q

Enzymes are highly specific in what?

A

both binding chiral substrates and in catalyzing their reaction

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16
Q

Why does enzyme specificity arise?

A

because enzymes, by the virtue of their inherent chirality (proteins consist of only L-amino acids), form asymmetric active sites.

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17
Q

If the YAD reaction is carried out with deuterated ethanol, the product NADH is what?

A

Deuterated

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18
Q

Many organisms are unable to synthesize certain portions of essential cofactors and therefore these substances must be present in the organism’s diet; thus they are _____

A

vitamins

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19
Q

many coenzymes are what?

A

growth factors for microorganisms or substance that cure nutritional deficiency diseases in humans and animals

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20
Q

The NAD+ component nicotinamide or its carboxylic acid analog nicotinic acid relieves what?

A

dietary deficiency disease in humans known as pellagra

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21
Q

Pellagra is characterized by what symptoms?

A

diarrhea, dermatitis, and dementia

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22
Q

Most animals can synthesize nicotinamide from what?

A

the amino acid tryptophan

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23
Q

Vitamins in the human diet that are coenzymes precursors are all ______

A

water soluble vitamins

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24
Q

Vitamin A and Vitamin D are what?

A

lipid-soluble vitamins

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25
Q

What vitamins are not components of coenzymes?

A

lipid-soluble vitamins such as vitamin A and D

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26
Q

What are the two ways an organism controls the catalytic activities of its component enzymes so it can coordinate its numerous metabolic processes?

A

1) Control enzyme availability

2) Control enzyme activity

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27
Q

The amount of a given enzyme depends on what? Which is controlled by what?

A

both its rate of synthesis and its rate of degradation. controlled by the cell

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28
Q

An enzyme’s catalytic activity may be directly controlled how?

A

through conformational or structural alterations.

29
Q

The rate of enzymatically catalyzed reaction is directly proportional to what?

A

to the concentration of its enzyme-substrate complex which varies with enzyme substrate concentrations and with enzyme’s substrate-binding affinity.

30
Q

The catalytic activity can be controlled by what?

A

through variation of its substrate binding affinity

31
Q

arbitrarily assigned number for YADH?

A

1: 1: 1: 17

32
Q

NAD+ oxidoreductase is waht?

A

an alcohol

33
Q

Oxidoreductase is what type of reaction catalyzed?

A

oxidation-reduction

34
Q

Transferase is what type of reaction catalyzed?

A

Transfer of functional groups

35
Q

Hydrolases is what type of reaction catalyzed?

A

hydrolysis reactions

36
Q

Lyases is what type of reaction catalyzed?

A

Group elimination to from double bonds

37
Q

Isomerases is what type of reaction catalyzed?

A

Isomerization

38
Q

Ligases is what type of reaction catalyzed?

A

Bond formation coupled with ATP hydrolysis

39
Q

The coenzyme Biotin is what type of reaction mediated?

A

carboxylation

40
Q

The coenzyme Cobalamin (B12) is what type of reaction mediated?

A

Alkylation

41
Q

The coenzyme, coenzyme A is what type of reaction mediated?

A

acyl transfer

42
Q

The coenzyme Flavin is what type of reaction mediated?

A

oxidation-reduction

43
Q

The coenzyme Lipoic acid is what type of reaction mediated?

A

acyl transfer

44
Q

The coenzyme Nicotinamide is what type of reaction mediated?

A

oxidation-reduction

45
Q

The coenzyme Pyridoxal is what type of reaction mediated?

A

Amino group transfer

46
Q

The coenzyme tetrahydrofolate is what type of reaction mediated?

A

One-carbon group transfer

47
Q

The coenzyme Thiamine pyrophosphate is what type of reaction mediated?

A

aldehyde transfer

48
Q

The vitamin Biotin has what coenzyme and causes what human deficency disease?

A

Biocytin causing human deficency disease is rare or unobserved

49
Q

The vitamin Cobalamin (b15) has what coenzyme and causes what human deficency disease?

A

cobalamin (b12) coenzymes) and cause pernicious anemia

50
Q

The vitamin Folic acid has what coenzyme and causes what human deficency disease?

A

Tetrahydrofolate and causes Megaloblastic anemia

51
Q

The vitamin Nicotinamide has what coenzyme and causes what human deficency disease?

A

Nicotinamide coenzymes and cause pellagra

52
Q

The vitamin Pantothenate has what coenzyme and causes what human deficency disease?

A

Coenzyme A and causing human deficency disease is rare or unobserved

53
Q

The vitamin Pyridoxine (B6) has what coenzyme and causes what human deficency disease?

A

pyridoxal phosphate causing human deficency disease is rare or unobserved

54
Q

The vitamin Riboflavin (B2) has what coenzyme and causes what human deficency disease?

A

Flavin coenzymes causing human deficency disease is rare or unobserved

55
Q

The vitamin Thiamine (B1) has what coenzyme and causes what human deficency disease?

A

Thiamine pyrophosphate and causes Beriberi disease

56
Q

urease catalyzes

A

hydrolysis of urea

57
Q

alcohol dehydrgenase catalyzes

A

the oxidation of alcohols to their corresponding aldehydes

58
Q

What are the 6 major classes of enzymes

A

1) Oxidoreductases
2) Transferase
3) Hydrolases
4) Lysases
5) Isomerase
6) Ligases

59
Q

Each enzyme is assigned

A

2 names Accepted name and systemic name, The accepted name is used for everyday use and the systemic name is used when ambiguity must be minimized.

60
Q

What is the systemic name of an enzyme?

A

name of substrate followed by word ending in -ase

61
Q

I number identification what does each number mean?

A
  • first number indicates enzymes major class
  • second number denotes its subclasses (glycosylases)
  • third number designates its sub-sub class (enzymes hydrolyzing )- and S-glycosylcompounds)
  • fourth number is enzyme’s arbitrarily assigned serial number in its sub-subclass.
62
Q

The common name alcohol dehydrogenase has the systemic name of what?

A

alcohol:NAD+ oxidoreductase

63
Q

Classification number of alcohol dehydrogenase?

A

1: 1: 1: 1

64
Q

dehydrogenases that catalyze reactions whose equilibrium constants with their natural substrates in the direction of reduction are <10^-12 M are almost always transfer _____?

A

pro-R hydrogen

65
Q

dehydrogenases that catalyze reactions whose equilibrium constants >10^-10 M generally transfer ____

A

pro S hydrogen

66
Q

The NADH hydrogen transferred in a enzymatic reaction is where?

A

almost certainly on the side of the nicotinamide ring facing the substrate.

67
Q

Enzymes are selective about the identities of the chemical groups on their substrate are called what?

A

geometric specificity (size and shape)

68
Q

Which is a more stringent requirement?

A

Geometric specificity

69
Q

Most enzyme catalyze how many enzymes

A

Most enzymes catalyze the reaction of a small range of related compounds; few enzymes are absolute;y specific for only one compound

biochemistry (6 decks)

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