Enzyme inhibitors Flashcards

1
Q

What are the uses of enzyme inhibitors in pharmaceutics (1)

A

inhibitors bind to an enzyme and decrease their activity

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2
Q

What are the types of enzyme inhibitors (5)

A
  1. irreversible
  2. reversible
  3. uncompetitive
  4. non-competitive
  5. competitive
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3
Q

How do irreversible and reversible enzyme inhibitors work (2)

A
  1. irreversible - enzyme binds to inhibitor to give an enzyme-inhibitor complex (e.g. sarin nerve gas permanently disables acetylcholinesterase)
  2. reversible - enzyme binds to inhibitor to give an enzyme-inhibitor complex, these are medicines used to target enzymes in various organisms
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4
Q

What are examples of reversible enzyme inhibitors (5)

A
  1. human - Slo-Phyllin for asthma
  2. bacterial - Samserin for tuberculosis
  3. viral - Zovirax for herpes
  4. fungal - Cancidas for thrush
  5. protozoal - Vaniqa for sleeping sickness
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5
Q

How do uncompetitive, competitive and non-competitive enzyme inhibitors work (4)

A
  1. uncompetitive - bind to enzyme-substrate complex
  2. competitive - bind to the enzyme through the active site
  3. non-competitive - bind to enzyme and enzyme-substrate complex through the allosteric site
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6
Q

What is allosteric regulation (2)

A
  1. During allosteric regulation, an effector molecule binds at a site other than the active site.
  2. Results in a conformational change of the enzyme that can enhance (+) activity if the effector is an activator or decrease (-) activity if the effector is an inhibitor.
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7
Q

In regulation via a control loop, what types of regulation can be visualised (3)

A
  1. If a biochemical pathway is considered to flow like a stream, then four types of regulation can be visualised:
  2. o positive or negative feedback from downstream products,
  3. o positive or negative feedforward from upstream substrates.
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8
Q

What is the definition of Vmax and KM (2)

A
  1. Vmax - the maximum reaction rate achieved when the substrate concentration is high enough that all the active sites are saturated with substrate
  2. KM - substrate concentration when the rate of reaction is half Vmax (the maximum velocity)
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9
Q

What are the effects on KM and Vmax of enzyme inhibitors (3)

A
  1. Uncompetitive - KM decreases, Vmax decreases.
  2. Competitive - KM increases, Vmax unchanged.
  3. Non-competitive - KM unchanged, Vmax decreases.
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