Drug targets - receptors, ion channels, enzymes, transporters Flashcards
combination of 2 lectures: drugs and enzymes & drugs and receptors
what is an enzyme inhibitor?
a molecule that binds to an enzyme and decreases its activity.
It prevents the substrate from entering the enzyme’s active site and prevents it from catalysing its reaction.
what are the 2 types of enzyme inhibitor?
- Irreversible inhibitors – react with the enzyme and change it chemically
- Reversible inhibitors – bind non-covalently and different types of inhibition are produced depending on whether these inhibitors bind to the enzyme, the enzyme-substrate complex, or both.
name a VERY COMMON drug that uses enzyme inhibition in its pathway
what enzyme does it inhibit and why
statin
statins inhibit the enzyme HMG-CoA reductase in the formation of cholesterol pathway
therefore lower lipids
example of enzyme inhibition: what does inhibiting ACE in the RAAS pathway cause?
inhibiting of Angiotensin converting enzyme
reduces angiotensin I from becoming angiotensin II
leads to reduction in blood pressure
what disease is commonly treated with enzyme inhibitor drugs?
parkinsons
inhibit dopamine degradation
what is the difference between passive and active transporters?
no energy required for a passive transporter
energy required for an active transporter
what are the 2 main types of passive transporter?
Symporter (cotransporter protein)
Channels
what is the main type of passive transporter?
ATP-ases
what are the 3 main types of cell membrane proteins transporters?
uniporter
symporter
antiporter
(symporter and anti porter are cotransporters)
does a uniporter use ATP?
yes - use energy from ATP to pull molecules in
does a symporter use ATP? give an example of a symporter
No
uses the movement of one molecule to pull in another molecule against a concentration gradient.
Both substances go in same direction
E.g the Na-K-Cl cotransporter (NKCC) in kidney
does a antiporter use ATP? give an example of a antiporter
No
one substance moves against its gradient, using energy from the second substance (mostly Na+, K+ or H+) moving down its gradient.
Substances go in opposite directions
how does a voltage gated ion channel work ?
Closed normally, then activated when exposed to depolarisation (action potential)
Calcium enters the cell at depolarisation, which activates Ca-sensitive K channels, which causes muscle contraction, and excitation of neurons etc.
what drug inhibits a voltage gated calcium channel in order to lower blood pressure?
amlodipine
(inhibits muscle contraction)
stopping Ca influx across cell membranes. This causes vasodilation, reduced peripheral vascular resistance and lowers BP
which channels are important in regulation of insulin secretion ?
voltage gates potassium channel
in the islets of langerhans in pancreas
(drugs blocking them triggers insulin secretion and therefore these are used in type 2 DM treatment)
how does the sodium pump work in the heart?
(Na/K ATP-ase)
Pumps 3 Na out of cell, 2 K into cell,
against both their concentration gradients therefore needs ATP
how does the sodium pump work in the heart?
(Na/K ATP-ase)
Pumps 3 Na out of cell, 2 K into cell,
against both their concentration gradients therefore needs ATP