Which amino acid can protonate and deprotonate at neutral pH?
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.
Histidine
Leucine
Glycine
Arginine
Proteins and Amino Acids