[Side-chain rotamers in protein alpha-alpha-hairpins and a mechanism of their selection].
The observed features of side-chain rotamer distributions in protein alpha-alpha-hairpins are described. It was found that in left-turned alpha-alpha-hairpins most side chains occupying d-positions have t-rotamers and those in g-positions g- -rotamers. In right-turned alpha-alpha-hairpins, most side chains in a-positions adopt g- -rotamers and those in e-positions t-rotamers. Analysis of these features enables us to conclude that selection of side-chain rotamers in alpha-alpha-hairpins depends on both the type of the alpha-helix packing and the residue position. The observed features can be explained taking into account the squeezing mechanism according to which interhelical interactions bring alpha-helices closer to each other and this effect squeezes side chains out of the helix-helix interface and as a result they adopt unique conformations.
Kargatov
A M
AM
Efimov
A V
AV
D019143:Evolution, Molecular; D017433:Protein Structure, Secondary / Q000502:physiology*; D011506:Proteins / Q000737:chemistry*; D020539:Sequence Analysis, Protein
D011506:Proteins