“…Compressibility of cavities of biopolymers, the contribution of the rigidity of the cavity to the conformational stability of the biopolymer can also be mimicked by studying structures of smaller molecules (Boldyreva, 2006). Attempts were made to describe the anisotropic compression of some of the crystalline amino acids by 'closing voids' (Dawson et al, 2005;Moggach, Allan, Morrison et al, 2005;Moggach, Allan, Clark et al, 2006;Moggach, Marshall & Parsons, 2006). Although any pressure-induced process can be expected to result in a structure with a higher density and smaller voids, crystalline amino acids are still not the best systems to study compression of cavities since their properties are to a large extent determined by dipole-dipole interactions and strong hydrogen bonds (OHÁ Á ÁO and NHÁ Á ÁO).…”