chapter 11 enzymes part 1 Flashcards

1
Q

who discovered the enzume

A

buchner

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2
Q

what Ea

A

the activation energy needed to reach and overcome a high energy transition state

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3
Q

wht determines if a reaction will occur or no

A

delta g
- spontaneous yes
nonspontaneous no

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4
Q

why is low Ea better

A

faster rate and the molecules can acheive that energy

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5
Q

an enzyme is also known as a

A

catalyst

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6
Q

what do enzymes do

A

they speed up the reactions

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7
Q

what has to happen for an enzume to catalyze a reaction

A

the free energy needs to de

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8
Q

what are the dos of enzymes

A

lower Ea
speed up time = speed up reaction
stabilize the transition state

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9
Q

what are the donts of the enzymes

A

dont change the delta g
don’t change the Keq(equilibrium constant )

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10
Q

what conditions do enzymes catalyze

A

mild conditions

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11
Q

what does it mean if an enzyme is stereospecific

A

the enzyme can catalyze reactions involving specific stereoisomers

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12
Q

explain the lock and key model of enzyme

A
  • enzyme is the lock substrate is the key
  • fischer
  • selectivity of chymotrypsin, trypsin, elastase
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13
Q

what are some limitations with lock and key model

A
  • doesn’t account for diverse substrates
  • doesn’t account for enzymes stabilizing transition state of the reaction
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14
Q

explain the induced fit model of enzyme

A

-koshland
- Substrate binds and causes a conformational change in the active site of the enzyme and it stabilizes the TS
- more than 1 s can be recognized by certain enzymes bc E can fit around different S

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15
Q

what are cofactors and what is their importance

A
  • ## non protein component that helps enzymes function
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16
Q

what are some examples of cofactors

A

metal ions
small organic molecules like coenzymes(vitamins)
- apoenzyme

17
Q

what makes a holoenzyme

A

apoenzyme + cofactor

18
Q

what factors affect enzyme activity

A

-temp
pH
cofactors
allosteric effectors
poiosns/ inhibitors

19
Q

what are the enzymatic catalysis mechanisms (6)

A

proximity effects
general acid base catalysis (gaba)
covalent catalysis
electrostatic stabilization
preferential stabilization of strained transition state
metal ion catalysis

20
Q

what is the proximity effect

A

positioning molecules close together for a rxn

21
Q

what is GABC

A

donating/ accepting an H+ by providing weak acid base to stabilize an unstable TS and thus lowering Ea

22
Q

what is covalent (nucleophillic) catalysis

A

enz active site provies nucleophile that forms a covalent Enz-s adduct that alters the reaction

23
Q

what is preferential stabilization of strained transition state

A

lowering Ea by stabilizing a conformationally unstable TS

24
Q

what is metal ion catalysis

A

catalyzing rxns by charge shielding; polarizing water to make it a better nucleophile etc
- bind substrates to orient them for catalysis

25
Q

what does freezing out the rotational translational motions do

A

increase the rate by a lot

26
Q

what are the amino acid side chains that participate in GABA

A
27
Q
A