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t.2 chemistry > unit 6 enzymes > Flashcards

unit 6 enzymes Flashcards

1
Q

enzymes usually have what structure

A

tertiary

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2
Q

reactants aka

A

substrates

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3
Q

intermediates are not

A

isolatable/purifiable

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4
Q

rate of rxn dependent on

A 
[reactants]
temperature
ph
activation E and the energy barrier
[products] (like if reach equilibrium)
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5
Q

catalysts help

A

lower energy barrier/activation energy, would make rxn more likely to occur

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6
Q

forward and reverse reactions occur

A

simultaneously at diff rates

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7
Q

() rxn rate are faster

A

initial

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8
Q

equilibrium state

A

concentration of products cannot increase further, forward and reverse reactions still occurring but NO NET CHANGE

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9
Q

equilibrium constant Keq

A

[products]/[reactants]

Keq=k1 (forward rxn) /k-1 (reverse rxn)

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10
Q

how Keq calculated

A

from equilibrium concentrations or ratio of rate constants

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11
Q

activation energy (Ea or delta G*)

A

when two reactants collide A+B, energy is realeased.

Must be greater than the energy barrier for the reaction to proceed

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12
Q

energy barrier

A

amount of energy required for the formation of products

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13
Q

what represents the net difference of energy

A

delta G

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14
Q

start low energy and end at high means it

A

cost us energy

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15
Q

+delta g means

A

cost us energy and is endergonic

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16
Q

-delta g means

A

released energy exorgonic

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17
Q

high energy to low means

A

released energy -G

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18
Q

reaction rate/ velocity

A

how fast the products are formed.

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19
Q

when measure velocity

A

very early in rxn (before reverse rxn)

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20
Q

units for velocity

A

mole/sec, umol/min

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21
Q

free energy change delta G (gibbs free energy)

A

difference between initial free energy of the reactants and products

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22
Q

delta g ultimately determines the

A

final concentrations of reactants and products BUT NOT THE REACTION RATE

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23
Q

what actually affects rate

A

activation energy

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24
Q

what is delta G0

A

change in free energy from standard state, 1.0 M concentrations of substrates and products to equilibrium

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25
Q

standard state STP

A

25 degrees C (298K) 1 stm ph 7

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26
Q

If free energy of products is lower than subtrates thes signs of delta G0 will be

A

negative -

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27
Q

if free energy is higher than products/products it will be

A

positive +

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28
Q

-delta g will occur () although () is not known

A

spontaneously, rate

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29
Q

enzymes are 6 things

A
  1. catalysts
  2. protein
  3. ph and temperature dependent
  4. specific
  5. saturable
  6. inhibitors, stimulators
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30
Q

catalysts 4 key things

A

increase rate of reaction
are not consumed
bind to substrates (reactants), lower Ea
don’t change Keq

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31
Q

things that like enzymes

A

bases, acids, metals, heat

32
Q

enzymes are mostly

33
Q

enzyme proteins are

A

rnas (ribozymes)

34
Q

holoenzyme

A

enzyme proteins have a prosthetic group attached to a apoprotein

35
Q

prosthesis means

A

to make something whole again

36
Q

ex of holoenzyme

A

enzyme change shapes because of b12

37
Q

metalloenzyme

A

a protein enzyme that prosthetic group is a metal

a type of holoenzyme

38
Q

enzyme as ph and temperature dependent means

A

has optimal ph and temperatures, and chemicals that denature proteins denature enzyme activity

39
Q

what kind of specificity do enzymes have

A

absolute (substrate) specificity or group specificity

or optical specificity

40
Q

what is optical specificity

A

the ability to distinguish between L- and D- forms of amino acids or sugars

41
Q

catalytic site

A

binds reactants and facilitates the reaction

42
Q

specificity is dictated by the () of the enzyme and substrate

A

3-D structure of the catalytic site

43
Q

cells require a minimum of () point attachment

44
Q

induced fit means

A

the substrate changes conformation in the catalytic site (NOT lock and key modle)

45
Q

what does it mean for the enzyme to be saturable

A

a reaction mixture (cytoplasm of cell) has a fixed amount of enzymes so the reaction rate increases with [substrate] to a point until all enzymes are busy

46
Q

activator enzymes do what

A

increase rate of reaction

47
Q

inhibitor enzymes do what

A

decrease rate of reaction

48
Q

enzyme inhibitors are generally

A

structural analogs of metabolites

49
Q

competitive inhibitors

A

inhibitor enzymes act by competing with the natural metabolite for the active site of the enzyme

50
Q

reversible competitive inhibitors

A

effect can be overcome by addition of more natural substrate

enzyme binds to something like fake glucose but they can get off and go to real glucose

51
Q

irreversible competitive inhibitors

A

it eliminates enzymes function, vmax is reduced

bind to fake glucose and cant get off

52
Q

4 things coenzymes can be

A
  1. secondary substrates required for the catalytic actions of certain enzymes
  2. inorganic or organic
  3. vitamin derivative
  4. prosthetic groups of enzymes
53
Q

ex of inorganic coenzymes

A

mg2+ ca2+ na+ cl-

54
Q

ex of organic coenzymes

A

NAD/NADH+H, FAD/FADH2, coASH

55
Q

what are the cofactors for B vitamins

A

NAD/NADH+H, FAD/FADH2, coASH

56
Q

ex of coenzyme as vitamn derivative

A

B vitamins especially

57
Q

how are the prosthetic groups of enzymes bounded

A

covalently (share electrons)

58
Q

allosteric effectors or ligands

A

substances other than substrates which regulate an enzymes activity by binding to the allosteric site of the enzyme

59
Q

what is an effector def

A

affects the effect of the enzyme

60
Q

allosteric site def

A

catalytic site or another site of enzyme

61
Q

binding the activator or inhibitor changes the enzymes () especially the catalytic site

A

conformation

62
Q

a kinetic plot demonstrates a non-linear

63
Q

positive allosteric kinetics shows

A

acceleration

64
Q

negative allosteric kinectics shows

A

deceleration

65
Q

binding of o2 to hemoglobin: when u bind one what else happens

A

you increase the chance of binding another

66
Q

enzyme kinetics asses what

A

how velocity of an enzymatic reaction is affected bya host of factors including substrate concentration, coenzymes, activators, inhibitors, ph, temperature, phase of the moon…

67
Q

experiments are done to obtain infor abouth

A

specificity of an enzyme for a particular substrate

mechanism of action.inhibition of enzyme activity

68
Q

michaelis menten equation

A

measures velocity of a reaction with increasing substrate concentrations keeping ph and temperature at optimum

69
Q

what is the actual michaelis menten equation

A

v=Vmax[S] / (Km+ [S])

70
Q

the substrate with the () Km (michaelis) is favored

A

lower = greater affinity

71
Q

what is Km

A

the [substrate] that produces a velocity of 1/2 max

= how strong an affinity an enzyme has for tis subtrate

72
Q

lineweaver-burk (double reciprocal) plot

A

1/v = (Km/Vmax [S]) + 1/Vmax

aka y=mx+b’p[;

73
Q

what does lineweaver-burk remove

A

removes the uncertainty of the vmax plateau of michaelis-menten eq.

74
Q

with lineweaver burk plot how do u find vmax

A

when u hit the velocity/y axis

75
Q

with lineweavers burk plot how get km

A

when it his the substrate axis

76
Q

michaelis menten and lineweaver burk are only good for () kinets because additional substrate binding (o2 to hb) may alter rate of reaction

A

non-allosteric

77
Q

what are the 4 types of enzme naming

A 
trivial name (chymotrypsin)
hybrid name (substrate + ase)
descriptive name (substrate + description + ase lactate dehydrogenase)
IUB systematic classification and nomenclature

t.2 chemistry (3 decks)

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