Enzymes Flashcards

1
Q

How do enzymes specify a chemical reaction?

A
  1. Site of occurrence - location (intracellular/extracellular)
  2. Rate of reaction - amount of active enzyme present
  3. Reaction time - state (active/inactive)
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2
Q

What are the 2 enzymes responsible for synthesis and degradation of acetylcholine?

A

ChAT: for synthesis (acetyl CoA +Choline -> Ach + CoA)
AChE: for degradation (Ach + H2O -> Choline + acetic acid)

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3
Q

Sites present on an enzyme

A
  1. Active site - binding of substrate
  2. Binding site - for coenzyme/cofactor
  3. Regulatory site - for activator/inhibitor
  4. Catalytic site - provide chemical environment
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4
Q

2 ways for an enzyme to function as a catalyst

A
  1. Provide alternative pathway with lower activation energy
  2. Mechanical straining of molecule in catalytic site
    - > change shape to facilitate change of structure
    - > accounts for the specificity of enzyme
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5
Q

Ways of changing accessibility of enzyme

A

Introduce small structural changes
1. Phosphorylation - fast, reversible
2. Cleavage of peptide bond - fast, irreversible
3. Activating/Inactivating enzyme - by activator/inhibitor
Adjust total amount of enzyme
4. Change rate of synthesis and degradation - slow, irreversible (long-term regulation)`

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6
Q

What is positive influence? When does it occur? What curve would it demonstrate on graph?

A

Occurs on oligomeric enzyme with multiple subunits

  • > bound subunit can exert positive influence on neighbouring subunits to increase the affinity of substrate
  • Sigmoidal curve*
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7
Q

What do allosteric regulators do?

A

+ allosteric regulators:
put oligomeric enzyme in active site -> demonstrate more sigmoidal curve
- allosteric regulators:
less sigmoidal curve, lengthens initial phase

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