Inhibitors

Question 1

What effect do competitive inhibitors have to Michaelis-Menten curves?

Answer 1

-Vmax unchanged
-KM increased
-kcat unchanged

Question 2

What effect do allosteric inhibitors have to Michaelis-Menten curves?

Answer 2

-Vmax reduced
-KM roughly the same
-kcat reduced

N/B: Can look like competitive inhibitors -use structural and mutational analysis to determine

Question 3

What is the observed rate of an enzyme reaction dependent on?

Answer 3

substrate conc

-directly proportional to fraction of sites filled at one moment in time

Question 4

What is the cellular response of a receptor like?

Answer 4

complex

response not always directly proportional to number of sites filled

Question 5

What is an endogenous agonist?

Answer 5

the intended ligand that binds at the orthosteric site of a receptor
-has intended response

Question 6

What is an antagonist?

Answer 6

ligand that doesn’t produce a signal

Question 7

What is a reverse agonist?

Answer 7

ligand that caused the opposite signal to the one the agonist would cause

Question 8

Inhibitor of peptide deformylase

Answer 8

Competitive
-mimics Met-Ala-Ser tripeptide
-co-ordinates with Fe2+
-can’t be hydrolysed

Question 9

Inhibitor of mitochondrial isocitrate dehydrogenase 2 mutant

Answer 9

Allosteric
-binds between two subunits of IDH2 dimer
-open form stabilised, can’t produce any toxic 2-hydroxyglutarate