Lecture 7 - Ligand binding

Question 1

Communication in the cell or between cells is ultimately achieved through

Answer 1

binding reactions in which a ligand binds to a macromolecule

Question 2

Typically the ligand is a

Answer 2

small organic molecule or a metal ion that binds to a protein

Question 3

The majority of interactions in biochemical systems begin with

Answer 3

binding of a ligand to a protein

Question 4

In pharmacology, binding of a _____ to a _____ is one of the most common and important questions envisioned

Answer 4

drug; target

Question 5

Biochemists express ligand affinities in terms of

Answer 5

dissociation constant (Kd)

Question 6

Kd =

Answer 6

1/K

Question 7

Kd is expressed in units of

Answer 7

concentration (M)

Question 8

Binding constants (K) in biochemical reactions vary by

Answer 8

orders of magnitude

Question 9

Enzyme-substrate interactions typically have Kd values from

Answer 9

0.1 uM to 1 mM

Question 10

Receptor-ligand interactions typically have Kd values from

Answer 10

0.1 nM to 10uM

Question 11

DNA-protein interactions typically have Kd values from

Answer 11

1 pM to 10 nM

Question 12

The smaller the Kd, the

Answer 12

stronger the protein-ligand interaction

Question 13

One of the strongest interactions known in a biochemical system is between

Answer 13

biotin and streptavidin

Question 14

The binding curve is the ______ plotted against the _______

Answer 14

specific binding; free ligand concentration

Question 15

If we have a protein with one binding site for a ligand, the number of ligands bound per site depends on

Answer 15

1. Ligand concentration in solution
2. Binding constant, K

Question 16

The number of ligands bound per site is called the

Answer 16

fractional saturation (ϴ)

Question 17

The approach to saturation is controlled only by the

Answer 17

binding constant, K

Question 18

Kd represents the concentration of the ligand at which the protein is

Answer 18

half saturated

Question 19

The binding constant (K) represents the ________ of the ligand for its binding site on the protein

Answer 19

intrinsic affinity

Question 20

Antagonist

Answer 20

A substance that interferes with or inhibits the physiological action of another

Question 21

Proton pump inhibitors (PPIs) inhibit

Answer 21

the H+/K+ ATPase pump that transports protons across membranes

Question 22

Ligands can be ______ or ______

Answer 22

agonists; antagonists

Question 23

Four different types of ligands

Answer 23

1. Full agonist
2. Partial agonist
3. Antagonist
4. Inverse agonist

Question 24

Full agonists result in

Answer 24

a 100% response

Question 25

Partial agonists cannot

Answer 25

achieve maximal response

Question 26

The EC50 for a partial agonist is the

Answer 26

ligand concentration that results in 50% of the partial agonists full response

Question 27

Full and partial agonists often bind to

Answer 27

the same binding site on a receptor

Question 28

Antagonists bind to a receptor and cause

Answer 28

no response

Question 29

An antagonist can be used to

Answer 29

block the binding of an agonist

Question 30

As the concentration of the antagonist increases, the response of the agonist

Answer 30

decreases

Question 31

An antagonist drug can be used to decrease the response of

Answer 31

a receptor

Question 32

GPCR stands for

Answer 32

G protein coupled receptors

Question 33

Serotonin receptors are GPCRs that

Answer 33

mediate both excitatory and inhibitory neurotransmission

Question 34

Antagonists have different ______ for their receptor targets

Answer 34

potencies

Question 35

IC50 means

Answer 35

half maximal inhibitory concentration

Question 36

Constitutive receptors can

Answer 36

cause a response without a ligand being bound

Question 37

An inverse agonist decreases the

Answer 37

constitutive receptor response to 0%

Question 38

The inverse agonist has the capability to completely

Answer 38

shut down a receptor

Question 39

The difference between an antagonist and an inverse agonist is that an antagonist results in

Answer 39

no response