Figure 10.
Preferred {X1,X2} rotameric states of the R1 side chain on solvent-exposed helical sites. Rotamers observed at lattice contact and noncontact sites are shown as filled and open circles, respectively. The figure includes data from twelve previously reported structures of the R1 side chain at helical surface sites in T4L,16–18 and the six structures of 131R1 and 151R1 observed in this study. This number includes structures of R1 obtained at a given site at two different temperatures (i.e., 115R1, 131R1, and 151R1), different rotamers at a given site (e.g., 131R1), and the structure of R1 at a given site differing by an alanine substitution at a nearby residue (i.e., 115R1/R119A).