Ornithine transcarbamoylase is a trimeric enzyme composed of identical subunits which catalyzes the synthesis of L-citrulline from carbamoyl phosphate and ornithine. Both substrates display typical Michaelis-Menten kinetics with this enzyme. However, a mutation changing arg106 to gly106 causes the enzyme to display sigmoidal kinetics in a substrate-dependency curve.

A.Offer a reasonable interpretation of the structural effects of this mutation on the enzyme that explains this observation.

B.How would the Km of the mutated enzyme relate to the Km of the normal enzyme?

C.Offer possible evolutionary ramifications of this observation.