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Science for shegs > Enzymes > Flashcards

Enzymes Flashcards

No questions on multisubstrate mechanisms

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1
Q

What is significant about enzymes being globular proteins?

A

It means they are generally soluble

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2
Q

What is a cofactor?

A

Non-protein component needed by the enzyme to work

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3
Q

What is a coenzyme?

A

Complex organic molecule

Takes part in the reaction but is not the enzyme

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4
Q

Coenzymes are usually produced from…

A

Vitamins

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5
Q

Define a prosthetic group.

A

Non-protein group covalently bonded/tightly bound to an enzyme

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6
Q

True/False

A prosthetic group is a type of cofactor?

A

True

PG’s are covalently bonded cofactors

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7
Q

What is the Apoenzyme?

A

Protein component of enzyme that contains a cofactor

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8
Q

What is the Holoenzyme?

A

Whole enzyme

Apoenzyme + any cofactors

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9
Q

True or false

There is 6 classes of enzymes based on the location of the enzyme.

A

False

6 classes based on the type of reaction the enzyme carries out

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10
Q

What is a Ligase Enzyme?

A

Formation of C-C, C-S, C-O, C-N bonds

Bond making/breaking enzyme

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11
Q

What is the significance of whether G is positive or negative?

A

Shows spontaneity

Negative = Spontaneous

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12
Q

What is the free energy equation?

A

/\G = /\H - T*/\S

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13
Q

True or false

If E= ‘energy barrier’ is applied to molecule in its ground state, then it will undergo a reaction and change to product.

A

False :(

It will reach transition state

Can either react to form product, OR revert back

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14
Q

How do enzymes reduce activation energy?

A

Entropy reduction
Desolvation
Induced fit

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15
Q

Kachow or Kerchoo

M-M equation assumed that K2 is slower than K1/K-1 so the RDS is:

ES —> E + P

A

Kachow

Thus rate is proportional to [ES]

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16
Q

Give the word definition of the Michaelis constant.

A

Substrate concentration when initial reaction velocity is half of Vmax

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17
Q

Give the numerical definition of the Michaelis constant.

A

Km = K(-1) / K(1)

18
Q

What does a low Km value indicate?

A

Enzyme has high affinity for Substrate

19
Q

What does a high Vmax indicate?

A

Very fast enzyme

20
Q

Describe an enzyme with high Km and high Vmax.

A

Very fast enzyme that is very bad at grabbing the substrate

21
Q

How are the Lineweaver-Burk plot and Michaelis-Menten equation linked?

A

L-B is double reciprocal plot of M-M equation

22
Q

Vo = (Vmax*[S]) / (Km + [S])

L-B or M-M?

A

M-M

23
Q

What is an Isoenzyme?

A

Two different enzymes that catalyse the same reaction

24
Q

Blow your load or Hit the road

Hexokinase is actually Glucokinase IV.

A

Hit the road

Glucokinase is a type of hexokinase enzyme

Hexokinase IV

25
Q

Glucokinase is found where?

A

Liver

26
Q

Describe why Glucokinase having a high Km + Vmax and hexokinase having a low Km + Vmax allows the body to respond to fluctuating [Glc].

A
  • After meal - [Glc] goes up
  • Hkase already working at Vmax
  • Gkase able to respond proportionally as extra Glc is left for it
27
Q

What reaction do Glucokinase and Hexokinase catalyse?

A

Glc + ATP —> G-6-P + ADP

28
Q

What effect does phosphorylation of Glc have?

A

Traps Glc

Transporters don’t recognise G-6-P

29
Q

What experimental method can be used to study isoenzymes or separate complex mixtures of enzymes?

A

Electrophoresis

30
Q

What is a ternary complex?

A

When both substrates are in the same complex

E + S’ + S” <==> ES’S”

31
Q

What is an Allosteric enzyme?

A

Multiple active sites

32
Q

Gucci gang or itchy wang

Cooperative binding: one substrate binding to one active site causes change in the other active sites, allowing more substrates to join

A

Gucci gang gucci gang gucci gang gucci gang

33
Q

What is the difference between an Un-competitive and a non-competitive inhibitor?

A

NC - binds onto allosteric site causing change in AS

UC - binds on after substrate and prevents interaction from taking place (as efficiently)

34
Q

What is the advantage of transition state analogues?

A

Easier for enzyme to bind to molecule in transition state shape than normal shape

35
Q

What 2 forms of inhibition can enzymes use to regulate their pathways?

A

Feedback inhibition

Allosteric inhibition

36
Q

How does feedback inhibition work?

A

Product of a pathway, or key stage, can inhibit enzyme at start

Stops more of the product being made

37
Q

True or false

Allosteric control of enzymes always involves inhibition of the enzyme.

A

False

Effectors can either be activators or inhibitors

38
Q

Why are many enzymes phosphorylated?

A

Fine tunes enzyme function

Adaptation to cellular conditions

39
Q

What is proteolytic cleavage?

A

Cleavage of inactive proenzyme to form active enzyme

40
Q

Why is proteolytic cleavage useful?

A

Prevents enzymes damaging cells or generally fucking stuff up

Eg: Digestive enzymes

41
Q

What 3 ways are enzyme molecules modulated/controlled?

A

Proteolytic cleavage
Covalent modification (phosphorylation)
Allosterically

Science for shegs (28 decks)

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