Enzymes as Drug Targets

Question 1

What’s the cell membrane also known as?

Answer 1

Plasma membrane

Question 2

Is the cell membrane permeable

Answer 2

Yes its selectively permeable

Question 3

What does the cell membrane consist of

Answer 3

Lipid bilayer, phospholipids ,cholesterol and proteins

Question 4

What’s the lipid bilayer consist of?

Answer 4

Phospholipids arrange themselves in a double layer with hydrophilic heads and hydrophobic tails facing inwards

Question 5

What’s the role of proteins in the cell membrane

Answer 5

transport molecules, structural support and signal transduction

Question 6

What’s a drug target

Answer 6

Specific molecules or structures within the body that drugs interact with to produce a therapeutic effect

Question 7

What molecules do drug targets include

Answer 7

enzymes
receptors
ion channels
nucleic acid
cell membrane: bilayers
Transporters

Question 8

Define enzyme inhibitors

Answer 8

Substances that bind to enzymes and decrease their activity

Question 9

How do enzyme inhibitors decrease enzyme activity

Answer 9

By slowing down or blocking enzyme catalysis

Question 10

True or false: Most of the drugs currently used are enzyme inhibitors

Answer 10

true

Question 11

What percentage of all current drugs are enzyme inhibit targets

Answer 11

47%

Question 12

What are inhibitors

Answer 12

Molecules that resemble the substrate or product and bind to the active site therefore interfering with catalysis slowing enzymatic reactions

Question 13

True or false : Drugs are not reversible enzyme inhibitors

Answer 13

false

Question 14

Describe process of aspirin

Answer 14

Inhibits the enzyme that catalyses the first step in the synthesis of prostaglandins

Question 15

What does the concentration of inhibitor needed depend on

Answer 15

How tightly inhibitor binds to enzyme

Question 16

What are the 2 types of inhibitors

Answer 16

Irreversible
Reversible

Question 17

Define reversible enzyme

Answer 17

Inhibition involves equilibrium between enzyme and inhibitor creating an equilibrium constant being the measure of affinity of the inhibitor for the enzyme

Question 18

What are 3 types of Reversible inhibition

Answer 18

Competitive
Uncompetitive
Non competitive

Question 19

Define Competitive inhibitor

Answer 19

A substance that competes with the substrate for binding to the active site of the enzyme

Question 20

Define non-competitive enzyme

Answer 20

Substance that binds to an enzyme only after the enzyme has already formed a complex with its substrate at the allosteric site and reduces enzyme activity

Question 21

Define uncompetitive

Answer 21

Substrate binds to active site and changes the shape to allow the inhibitor to bind

Question 22

Define irreversible inhibitor

Answer 22

Binds to an enzyme that permanently inactivates the enzyme

Question 23

How does an irreversible inhibitor permanently inactivate the enzyme

Answer 23

By forming a covalent bond with the enzyme or destroy functional group that form stable non covalent association

Question 24

Define receptors

Answer 24

are specialised proteins on membrane that receive signals from outside the cells

Question 25

True or false ; each receptor is specific to ligands?

Answer 25

true

Question 26

What can the 2 signals on receptors be

Answer 26

chemical or physical

Question 27

What are ligands

Answer 27

Molecules that bind to receptors

Question 28

What are the 2 classifications of ligands?

Answer 28

Agonist antagonist

Question 29

What are agonists

Answer 29

bind and switch on a receptor

Question 30

What are antagonists

Answer 30

Bind but do not switch on receptor -inhibits receptor response

Question 31

What are the 4 types of receptors?

Answer 31

-Ligand gated ion channels -G protein coupled receptors -enzyme linked receptors -nuclear receptors

Question 32

What are ligand-gated ion channels

Answer 32

Type of transmembrane protein that allows ions to flow across the cell membrane

Question 33

What does the ligand gated channel do

Answer 33

Ligand induces conformational change in the channel protein - usually reversible closing the pore back to resting state termination ion flow

Question 34

What are G-coupled receptors

Answer 34

Large family of cell surface receptors that transmit signals from outside the cell to the inside triggering various cellular responses

Question 35

Function and structure of the receptor in a G-coupled protein

Answer 35

Bundle of trans-membrane helices with a binding site for it's signal outside the cell and inside has an enzymatic site for the G-protein

Question 36

Define Heterotrimer

Answer 36

Protein complex that consists of 3 different subunits

Question 36

True or false: the G-protein is membrane bound and is a heterotrimer

Answer 36

true

Question 37

In a G-protein where does the alpha-subunit bind to

Answer 37

GDP in the resting state

Question 38

Process of a receptor turning on

Answer 38

1-GPCR binds to ligand to undergo conformational change 2-Change in receptor allows receptor to interact with G-protein where alpha sub unit binds to GDP in resting state. 3- activation of G-protein- by receptor facilitating exchange GDP TO GDT on alpha sub unit 4- GTP bound to sub unit , G-protein undergoes conformational change causing it to dissociate in two parts - GTP-bound alpha sub unit and beta dimer These can interact with intracellular signalling pathways

Question 39

What does the G-protein dissociate to when activated

Answer 39

-GTP-bound alpha sub unit and beta dimer

Question 40

Describe the process of the receptor when its turned off

Answer 40

Hydrolysis of GTP to GDP Re association of sub units Receptor returns to inactive state

Question 41

Explain what happens in the hydrolysis of GTP to GDP

Answer 41

After G-protein has been activated the alpha sub unit slowly hydrolyses GTP and GDP inactivating the alpha sub unit