pH = pKa + log([A-]/[HA]) pKa is the pH when half of the molecules are deprotonated and there is an equal concentration of acid and conjugate base [HA] = [A-].
When the pKa > pH, the molecule will be protonated and when pKa < pH the molecule will be deprotonated. For amino acids, the pKa of the carboxyl group is ~2 and the pKa of the amino group is ~9-10.