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
2
Q
What are the types of enzyme inhibitors (5)
A
- irreversible
- reversible
- uncompetitive
- non-competitive
- competitive
3
Q
How do irreversible and reversible enzyme inhibitors work (2)
A
- irreversible - enzyme binds to inhibitor to give an enzyme-inhibitor complex (e.g. sarin nerve gas permanently disables acetylcholinesterase)
- reversible - enzyme binds to inhibitor to give an enzyme-inhibitor complex, these are medicines used to target enzymes in various organisms
4
Q
What are examples of reversible enzyme inhibitors (5)
A
- human - Slo-Phyllin for asthma
- bacterial - Samserin for tuberculosis
- viral - Zovirax for herpes
- fungal - Cancidas for thrush
- protozoal - Vaniqa for sleeping sickness
5
Q
How do uncompetitive, competitive and non-competitive enzyme inhibitors work (4)
A
- uncompetitive - bind to enzyme-substrate complex
- competitive - bind to the enzyme through the active site
- non-competitive - bind to enzyme and enzyme-substrate complex through the allosteric site
6
Q
What is allosteric regulation (2)
A
- During allosteric regulation, an effector molecule binds at a site other than the active site.
- 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.
7
Q
In regulation via a control loop, what types of regulation can be visualised (3)
A
- If a biochemical pathway is considered to flow like a stream, then four types of regulation can be visualised:
- o positive or negative feedback from downstream products,
- o positive or negative feedforward from upstream substrates.
8
Q
What is the definition of Vmax and KM (2)
A
- Vmax - the maximum reaction rate achieved when the substrate concentration is high enough that all the active sites are saturated with substrate
- KM - substrate concentration when the rate of reaction is half Vmax (the maximum velocity)
9
Q
What are the effects on KM and Vmax of enzyme inhibitors (3)
A
- Uncompetitive - KM decreases, Vmax decreases.
- Competitive - KM increases, Vmax unchanged.
- Non-competitive - KM unchanged, Vmax decreases.