Molecular targets 2: ions and enzymes

Question 1

What is the intracellular concentration of K+

Answer 1

150mM

Question 2

Is intracellular K+ concentration greater or less than extracellular K+ concentration?

Answer 2

GREATER

Question 3

Potassium as volted gated ion channels - how do they regulate the cell

Answer 3

• Most diverse family of ion channels: more then 70 different genes code it
• Regulate the cell through:
• Freq and shape of APs
• Secrete hormones
• Secrete NTs
• Membrane potential

Question 4

Sodium as volted gated ion channels

Answer 4

• Encoded by atleast 10 genes
• Present in membranes of most cells
• Comprise of one pore-forming α subunit, which may be associated with either one or two β subunits

Question 5

Voltage-gated ion channels: Calcium: Three families,

Answer 5

Question 6

Voltage-gated ion channels: Targets for therapy

Answer 6

Question 7

What are channelopathies and name some examples

Answer 7

Diseases that occur when voltage gated ion channels malfunction

Question 8

What is a ligand-gated channel

Answer 8

• Found in membranes of cells particularly neurones
• They open and close in response to a specific ligand e.g. a NT or other signalling molecules
• Causes an ionic influx
• They are heteromeric assemblies: composed of different subunits
• An example is nicotonic acetylcholine receptor is activated by acetylcholine

Question 9

Physiology of LGIC

Answer 9

• They contain pores
• Ligand binds to these pores causes conformational change
• Which causes an ion influx via electrochemical gradient
• LGICs are fast synaptic transmissions in the NS and at somatic neuromuscular junction

Question 10

LGIC structure

Answer 10

Question 11

Answer 11

Question 12

Answer 12

Question 13

Enzyme kinetics: Whats Vmax and Km

Answer 13

Question 14

How can we alter enzyme activity? and how does this effect enzyme kinetics

Answer 14

• Via Enzyme inhibition: molecules that rude or inhibit enzyme activity
  1. Competitive inhibitors: bind to enzyme at AS, Km increases, Vmax stays the same
  2. Non-competitive inhibitors: binds to allosteric site. Km same

Question 15

Enzymes as drug targets

Answer 15

Question 16

What is the role of the alpha-1 subunit in voltage-gated calcium channels?

Answer 16

The alpha-1 subunit in voltage-gated calcium channels forms the pore and provides the extracellular binding sites for most agonists and antagonists.

Question 17

Explain how ligand-gated ion channels differ from voltage-gated ion channels.

Answer 17

Ligand-gated ion channels are opened by the binding of a specific ligand to the channel, while voltage-gated ion channels open in response to changes in the membrane potential.

Question 18

What is the mechanism of action of aspirin in treating inflammation?

Answer 18

Aspirin inhibits cyclo-oxygenase enzymes, which are involved in the synthesis of prostaglandins, molecules involved in the inflammatory response. Aspirin leads to the reduction of prostaglandin production.

Question 19

How does penicillin inhibit bacterial growth?

Answer 19

Penicillin irreversibly inhibits DD transpeptidases, an enzyme involved in the synthesis of bacterial cell walls. By preventing the formation of new cell walls, penicillin causes bacterial cells to die.