The side chain of ________ has a pKa in the physiological pH range and is therefore often involved in proton transfer during enzymatic catalysis. The side chain of ________ has a pKa in the physiological pH range and is therefore often involved in proton transfer during enzymatic catalysis. His Glu Asp Arg
Histidine (his), Arginine (arg), Aspartic acic (asp) and Glutamic acid (glu) have 3 acidic hidrogens each one, but only his has one physiological in the pH range.