Question

Which of the following statements about the MWC model is false?

a. it involves the enzyme occurring in the two distinct conformations when the allosteric regulator is absent

b. it involves the enzyme occurring in an R state (performs catalysis well) and a T state (performs catalysis poorly)

c. it involves a conformational shift in the prescence of allosteric regulator

d. it involves a higher population of the T state than the R state when allosteric regulator is not present

e. it involves a major conformational shift from R to T when allosteric regulator is added

Answer 1

Monod-Wyman-Changeux model (MWC model): It gives allosteric transition of proteins which contains the same subunits

a. it involves the enzyme occurring in the two distinct conformations when the allosteric regulator is absent

True, The model is based on the idea that the enzyme exists in 2 different conformations in the absence of a regulator

b. it involves the enzyme occurring in an R state (performs catalysis well) and a T state (performs catalysis poorly)

True, R state is a relaxed state with higher surface area and the T state is Tensed state with less surface area thus making R highly catalytic and T less catalytic. Affinity for the ligand is higher in R state

c. it involves a conformational shift in the presence of an allosteric regulator

False, Regulator just shifts the equilibrium from one state to another

d. it involves a higher population of the T state than the R state when allosteric regulator is not present

False. It depends upon the concentration of ligands. Presence of ligands shifts the equilibrium towards R state

e. it involves a major conformational shift from R to T when allosteric regulator is added

False, just shifts the equilibrium from one state to another