[Role of the structural context in selection of hydrophobic side-chain rotamers in a- and d-positions of alpha-helices].

The study shows that in coiled-coil proteins the distribution of hydrophobic side-chain rotamers in a- and d-positions of alpha-helices is strongly dependent on the mutual arrangement of the a-helices. In coiled-coil dimers, where a-helices are packed "face-to-face", most side chains occupying a-positions adopt t-rotamers, and those in d-positions adopt g- -rotamers. In tetramers, where alpha-helices are packed "side-by-side", most side chains in a-positions adopt g- -rotamers and those in d-positions adopt t-rotamers. These features can be used for prediction of side-chain rotamers in protein modeling and design.