Tanford gives a complete set of "expected" pK values in his 1962 review on the analysis of protein titration curves (1). The pK values are derived from a variety of small model compounds, as reported by Cohen and Edsall (1943) or Edsall and Wyman (1958) (2,3). These values are corrected for electrostatic effects and represented expected pK values in aqueous solution at or near 25 oC.