“…In order to extend the relatively sparse thermodynamic data set available in the literature for crystalline peptides (Hutchens et al, 1969a,b;Domalski, 1972;Finegold and Kumar, 1981;Roles and Wunderlich, 1991;Diaz et al, 1992;Zhang et al, 1996;Di Lorenzo et al, 1999;Drebushchak et al, 2008), the group additivity method for estimating thermodynamic properties of organic compounds (e.g., Benson and Buss, 1958;Benson, 1968;Hearing, 1988, 1993;Amend and Helgeson, 1997b;Richard and Helgeson, 1998) has been adopted. In this approach, the contribution of a group of atoms in a molecule to the thermodynamic properties of the entire compound is determined.…”