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Biochem > Enzymes > Flashcards

Enzymes Flashcards

1
Q

Globular proteins (Structure)

A

Complex, ball like

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2
Q

Fibrous proteins (Structure and Function)

A

Simple, struture is function

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3
Q

What are Enzymes made of

A

Proteins + RNA molecules

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4
Q

How much can enzymes increase the rate of reaction by?

A

10^17

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5
Q

Examples of enzyme action

A

Food Breakdown (Hexokinase), Biosynthesis (Polymerase)

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6
Q

Phenylketorunia (PKU)

A
  • Mutation in Phenylalanine Hydroxylase
  • Toxic build up in brain -> intelectual disabilities + seizures
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7
Q

McArdle Disease

A

Genetic Disorder, affects skeletal muscle, deficiency in myophosphorylase

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8
Q

Components of Active site

A

Binding Site = Binds and orients substrate
Catalytic site = Reduce chemical activation energy

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9
Q

Active site properties and abilities

A
  • Non - polar
  • hydrogen bonding, Hydrophobic interactions, van der Waals, electrostatic, reversible covalent bonding
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10
Q

What is the allosteric site

A

Distinct from active site, induces a conformational change (change in active site)
Mechanism of regulation (Activates or inhibits reactions)
Can act as a feedback mechanism

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11
Q

What is a Cofactor

A

Any inorganic factor required for enzyme activity or protein function

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12
Q

What is a Coenzyme

A

An organic cofactor which is directly involved in enzyme catalysed reactions

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13
Q

What is a prosthetic group

A

Covalently associated non-protein constituent for a particular function

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14
Q

What is unique to a metalloenzyme

A

Cannot function without a metal ion in the active site (Example of a cofactor)

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15
Q

Co-Enzymes

A
  • Required by some enzymes of (optimal) activity
  • Typically organic molecules
  • Contains functionaliteis not found in proteins
  • Transiently bound (Not permenant)
  • May be altered during reaction - renewal
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16
Q

A Holoenzyme is formed up of (2 things)

A

Apoenzyme (inactive Enzyme)+ Cofactor

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17
Q

Function of enzyme group: Oxioreductase

A

Transfer of oxygen or hydrogen atoms or electrons from one substrate to another

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18
Q

Function of enzyme group: Transferases

A

Trasnfers functional groups from one substrate to another

19
Q

Function of enzyme group: Hydrolases

A

Hydrolysis of a substrate

20
Q

Function of enzyme group: Lyases

A

Addition or removal of a group to form a double bond

21
Q

Function of enzyme group: Isomerases

A

Transfer of groups between a molecule

22
Q

Function of enzyme group: Ligases

A

Bond formation coupled with ATP hydrolysis

23
Q

What is an exergonic reaction?

A

Spontaneous, produces more energy than input energy (Heat is released)
(-ΔG)

24
Q

What is an endergonic reaction?

A

Requires more energy input than it yields (Heat is absorbed)
(+ΔG)

25
Q

What is the activation energy

A

The initial energy required for a reaction (Exer or Endergonic) to occur

26
Q

What do enzymes do to the activation energy?

A

Reduce it

27
Q

What is the difference in activation energy called?

A

The Transition State

28
Q

What are the four main catalytic mechanisms?

A
  • Metal Ion
  • Catalysis by approximation
  • Covalent Catalysis
  • Acid Base Catalysis
29
Q

What does Catalysis by approximation do?

A

Brings substrate together

30
Q

What is V0

A

-Enzyme Velocity @ Time 0

31
Q

Properties of V0

A

> 10% of Substrate converted
fastest rate
Least amount of product created
Least amount of feedback inhibition

32
Q

Relationship between V0 and S

A

Higher S = Higher V0

33
Q

What is Km

A

Vmax/2 on the substrate concentration axis
Measure of enzyme affinity for substrate
Measure in units of concentration

34
Q

What does high Km indicate in terms of enzyme biding?

A

Weak binding -> Low affinity

35
Q

What does low Km indicate in terms of enzyme binding

A

Strong binding -> High affinity

36
Q

What happens when affinity increase (V0, rate of reaction)

A

Greater V0, therefore faster rate of reaction

37
Q

Small deviations in pH result in?

A

Much smaller activity

38
Q

What are competitive inhibitors?

A

Take the place of the substrate in the enzyme -> reduces rate of activity

39
Q

How can competitve inhibitors be overcome?

A

Increasing Substrate concentration

40
Q

What does a competitive inhibitor do to Vmax and Km

A

Vmax, remains unchanged
Km, increases so enzyme affinity for substrate is reduced

41
Q

What are non competitive inhibitors?

A

Inhibitors that bind in the allosteric site, changing the shape of the active site
Results in substrate not being able to bind

42
Q

What do competitive inhibitors do to Vmax and Km

A

Vmax is decreased, resulting in a decrease for Vmax/2
Km does not change however

43
Q

What is uncompetitive inhibition and how does it affect Vmax and Km

A

Inhibitor binds only to the enzyme/substrate complex
Decreases both Vmax and Km

44
Q

Other methods of enzymatic regulation

A

-Reversible covalent Modification
-Proteolytic ActivationZymogen
-Activation by Proteolytic cleavage
-Proteolytic activation

Biochem (6 decks)

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