title: Multistep modeling of protein structure:  application towards refinement of tyr-tRNA synthetase.
abstract: The scope of multistep modeling (MSM) is expanding by adding a least-squares minimization step in the procedure to fit backbone reconstruction consistent with a set of C-alpha coordinates.  The analytical solution of Phi and Psi angles, that fits a C-alpha x-ray coordinate is used for tyr-tRNA synthetase.  Phi and Psi angles for the region where the above mentioned method fails, are obtained by minimizing the difference in C-alpha distances between the computed model and the crystal structure in a least-squares sense.  We present a stepwise application of this part of MSM to the determination of the complete backbone geometry of the 321 N terminal residues of tyrosine tRNA synthetase to a root mean square deviation of 0.47 angstroms from the crystallographic C-alpha coordinates.
authors.affiliation: Department of Biophysics, Roswell Park Memorial Institute, Buffalo, New York 14263, USA.
authors.forename: S
authors.initials: S
authors.lastname: Srinivasan
authors.forename: M
authors.initials: M
authors.lastname: Shibata
authors.forename: M
authors.initials: M
authors.lastname: Roychoudhury
authors.forename: R
authors.initials: R
authors.lastname: Rein
mesh_terms: D003196:Computer Graphics; D003461:Crystallography; D016018:Least-Squares Analysis; D008958:Models, Molecular; D015394:Molecular Structure; D012984:Software; D014448:Tyrosine-tRNA Ligase
chemical_list: D014448:Tyrosine-tRNA Ligase