3.1 Papers
3.1.6 Chronological list
3.1.6.25 Eisenmenger, F., Argos, P., and Abagyan, R.A., (1993). A method to configure protein side-chains from the mainchain trace in homology modeling. J. Mol. Biol., 231, 849-860
Protein homology modelling typically involves the prediction of side-chain conformations in the modelled protein while
assuming a main-chain trace taken from a known tertiary structure of a protein with homologous sequence. It is generally
believed that the need to examine all possible combinations of side-chain conformations poses the major obstacle to
accurate homology modelling. Methods proposed heretofore use only discrete or limited searches of the side-chain torsion
angle space to mitigate the combinatorial problem and also rely on simplified energy functions for calculational speed. The
configurational constraints are typically based upon use of frequently observed torsion angles, fixed steps in torsion angles,
or oligopeptide segments taken from tertiary structural databanks that are similar in sequence and conformation with the
target structure. In the present work, a more fundamental approach is explored for several protein structures and it is
demonstrated that the combinatorial barrier in side-chain placement hardly exists. Each side-group can be configured
individually in the environment of only the backbone atoms using a systematic search procedure combined with extensive
local energy minimization. Tests, using the main-chain or both the main-chain and remaining side-chain atoms to calculate
low energy geometries for each residue, established the dominance of the main-chain contribution. The final structure is
achieved by combining the individually placed side-chains followed by a full energy refinement of the structure. The
prediction accuracy of the present homology modelling technique was assessed relative to other automated procedures and
was found to yield improved predictions relative to the known side-chain conformations determined by X-ray
crystallography.