Arginine is a basic amino acid containing the guanidino group.
Arginine is one of the basic amino acids.
Arginine is a basic amino acid and it contains a guanidino group in its side-chain.
Guanidino group has resonance in its structure which means it is quite a stable group.
The highly basic nature of arginine is due to the presence of the guanidino group in its side chain.
Arginine has three ionizable groups with pKa values of 2.17,9.04, and 12.48 for the alpha-carboxylic group, alpha-amino group, and side-chain respectively.
When pH is greater than the pKa values of the ionizable groups then these ionizable groups are present in the deprotonated states.
HCl is an acid and it decreases the pH of the arginine solution.
The arginine solution will resist the pH change around its pKa values such that the titration curve of 0.2 M arginine solution ( pH 14 ) with 1M HCl will be as follows:
