Which amino acid can protonate and deprotonate at neutral pH?
Histidine
Leucine
Glycine
Arginine
Ans. A. HistidineAmino acid which can protonate and deprotonate means those which can act as buffer.Amino acid whose pKa=pH of the medium has maximum buffering capacity.pKa of imidazole group of histidine is 6.5 - 7.4.At pH=7, Imidazole group of histidine can act as buffer.
Proteins and Amino Acids