The precision of calculated hydrophobic thicknesses and tilt angles are ~1 Å and 2°, respectively, as judged from their deviations in different crystal forms of the same proteins. The fluctuations of these parameters calculated within 1 kcal/mol around the global minimum of transfer energy are usually smaller than 2 Å and 4°, respectively (± values in all Tables of the database). The calculated tilt angles in homologous proteins differ by 2-16° depending on the size of the protein, its oligomeric state and percentage of sequence identity.
Figure 2. Deviations of calculated tilt angles in different crystal forms of the photosynthetic reaction centers from Rhodobacter sphaeroides (A), or in homologous photoreaction centers from different bacteria (B).