Nozaki Y & Tanford C, 1967
Nozaki and Tanford report a complete set of pK values in their classic methods paper treating the behavior of protein titrations (1). The pK values provided have been measured in a variety of small model compounds, and corrected for electrostatic effects and other structural features to give pK values that represent the ionizable group in isolation. The values reported are the intrinsic pK values of each ionizable group at 25 oC.
Amino acid pK values from Nozaki Y and Tanford C, 1967 (1).