Drugs - Enzymes And Transporters 16.11.23 Flashcards
What is an enzyme inhibitor?
An enzyme inhibitoris a molecule that binds to anenzymeand (normally) decreases itsactivity.
What are the 2 types of enzyme inhibitors?
Irreversible inhibitors and reversible inhibitors
How do irreversible inhibitors work?
Irreversible inhibitors usually react with the enzyme and change it chemically (e.g. viacovalent bondformation).
How do reversible inhibitors work?
Reversible inhibitors bindnon-covalentlyand different types of inhibition are produced depending on whether these inhibitors bind to theenzyme, the enzyme-substrate complex, or both.
Give 2 examples of a medication which are an enzyme inhibitor
Statins (blocks rate limiting step in cholesterol pathway)
ACE inhibition for lowering blood pressure,
What are the 3 main types of protein ports in cell membranes?
Uniporters
Symporters
Antiporters
How do uniporters transport molecules through cell membranes?
Use energy from ATP to pull molecules in
How do symporters transport molecules through cell membranes?
Use the movement in of one molecule to pull in another molecule against a concentration gradient
How do antiporters transport molecules through cell membranes?
One substance moves against its gradient, using energy from the second substance (mostly Na+, K+ or H+) moving down its gradient.
Give an example of a symporter
Na-K-Cl co-transporter (NKCC)
Define epithelial (sodium) channel (ENaC)
An (apical) membrane-bound heterotrimeric* ion channel selectively permeable to Na+ ions
*two set of three proteins
Where and what ions are transported via epithelial (sodium) channel (ENaC)
Causes reabsorption of Na+ ions at the collecting ducts of the kidney’s nephrons (also in colon, lung and sweat glands)
What drug blocks Epithelial (Sodium) channel (ENaC)
Amiloride (high affinity diuretic)
Where are voltage-gated (calcium) channels found?
Voltage-gated ion channels (VDCC) are found in the membrane of excitable cells (e.g., muscle, glial cells, neurons, etc.)
At physiological or resting membrane potential, are Voltage-gated (Calcium) channels normally open or closed?
Normally closed at resting membrane potential
When are Voltage-gated (Calcium) channels normally opened?
They are activated (i.e., opened) at depolarized membrane potentials (action potential)*.
A momentary change in electrical potential on the surface of a nerve or muscle cell, that occurs when it is stimulated, resulting in the transmission of an electrical impulse.
What drug blocks voltage-gated (calcium) inhibition?
Amlodipine - Amlodipine is an angioselective (Why is that important?) Ca channel blocker that inhibits the movement of Ca ions into vascular smooth muscle cells and cardiac muscle cells
This inhibits the contraction of cardiac muscle and vascular smooth muscle cells
Amlodipine inhibits Ca ion influx across cell membranes, with a greater effect on vascular smooth muscle cells
Causes vasodilation and a reduction peripheral vascular resistance, thus lowering blood pressure
Also prevents excessive constriction in the coronary arteries
