Needs-Work Review · Structure, function, and reactivity of biologically relevant molecules
In the catalytic mechanism of a serine protease, a histidine side chain removes a proton from the hydroxyl group of a serine side chain. What is the primary effect of this proton transfer?
AIt decreases steric hindrance around the substrate carbonyl.Your answer
BIt increases the nucleophilicity of the serine oxygen.Correct
Removal of the proton produces a negatively charged serine oxygen with greater electron density. This oxygen is therefore a stronger nucleophile and can attack the electrophilic carbonyl carbon of the substrate.