Enzymes Flashcards

1
Q

Define Cofactor:

A

Non-protein part of an enzyme needed for activity

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2
Q

Define Coenzyme

A

Complex organic molecule ususally made from vitamins

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3
Q

Prosthetic group:

A

Cofacter bound to or tightly associated with the enzyme

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4
Q

Apoenzyme:

A

Protein component of enzyme

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5
Q

What do enzymes do when they catalyze a reaction?

A
  • Reduce activation energy
  • Increase rate of spontaenous reactions
  • Increase movement toward equilibria
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6
Q

Define a ribozyme?

A

A type of enzyme with no protein component.

Catalytic RNA molecules

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7
Q

Examples of co-enzyme

A

FAD
NAD+
Coenzyme A

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8
Q

Holoenzyme?

A

Entire enzyme, i.e. both apoenzyme & cofactor

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9
Q

What do these enzyme classes do:

  • Oxidoreductases
  • Lyases
  • Ligases
A
Oxidoreductases = Transfer electrons
Lyases = Form or add groups to double bonds
Ligases = Form C-C,C-N,C-S,C-O bonds
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10
Q

What is gibbs free energy?

A

Basically the available or useful energy generated from a reaction
Spontaneous reactions have -ve deltaG values because they give out energy

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11
Q

To what state is the active site complementary to?

A

The molecules transition state

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12
Q

In what 3 ways do enzymes reduce activation energy?

A
  • Induced Fit
  • Desolvation
  • Entropy reduction
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13
Q

Explain induced fit:

A

Conformational changes in the enzyme force the substrate together or apart

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14
Q

Explain desolvation:

A

Strong H bonds bind the solvent & subsstrate together

The enzyme replaces these with weaker substrate-enzyme bonds

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15
Q

Explain entropy reduction:

A

Enzymes force the substrate into the correct orientation, this way theyre interaction isnt just down to chance

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16
Q

How do we plot enzyme kinetics graphs?

A
Initial velocity (Vo)
Against Substrate conc. (S)
17
Q

What is Km?

A

Michaelis Constant

[S] at half the max Vo

18
Q

Why does Vmax occur?

A

BEcause all the enzymes active sites are saturated with subtrate

19
Q

Michaelis-Menton equation:

A

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

20
Q

In what other way do we plot enzyme kinetics?

A

A lineweaver-Burke plot (doulbe reciprocal)

21
Q

Whats the equation for lineweaver-burke plots (think straight line):

A

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

22
Q

What does a small Km tell us?

A

The enzyme-substrate complex is very stable, i.e. the enzyme has a high affinity for its substrate

23
Q

What values of Km & Vmax do you want?

A

An efficient enzyme has a high Vmax & a low Km