| DISTANCE GEOMETRY AND DYNAMICAL SIMULATED ANNEALING | INITIAL STRUCTURES (5000) WERE CALCULATED USING THE DISTANCE GEOMETRY PROGRAMME DIANA, USING A SINGLE CYCLE OF REDUNDANT DIHEDRAL ANGLE RESTRAINTS [GUNTERT, P. AND WUTHRICH, K. (1991) J. BIOMOL. NMR 1, 447-456]. THE 100 STRUCTURES WITH LOWEST RESIDUAL RESTRAINT VIOLATIONS WERE THEN REFINED USING DYNAMICAL SIMULATED ANNEALING [NILGES, M. CLORE, G.M. AND GRONENBORN, A.M. (1988) FEBS LETT. 229, 317-324] IN X-PLOR. STRUCTURES WERE CALCULATED USING 419 NON-REDUNDANT INTERPROTON DISTANCE RESTRAINTS, 43 DIHEDRAL-ANGLE RESTRAINTS (27 PHI, 16 CHI1), AND 28 RESTRAINTS DEFINING 14 HYDROGEN BONDS, GIVING AN AVERAGE OF 13.2 RESTRAINTS/RESIDUE. THE ATOMIC RMS DIFFERENCES FOR RESIDUES 4 - 37 OF THE FINAL FAMILY OF 20 CONFORMERS WITH RESPECT TO THE MEAN COORDINATE POSITIONS ARE 0.22 /- 0.06 AND 0.62 +/- 0.08 ANGSTROMS FOR THE BACKBONE AND HEAVY ATOMS, RESPECTIVELY. THE CORRESPONDING PAIRWISE RMS DIFFERENCES ARE 0.31 +/- 0.07 AND 0.90 +/- 0.12 ANGSTROMS. RESIDUES 1 - 3 ARE DISORDERED. THE DEPOSITED STRUCTURES HAVE BEEN SUPERIMPOSED FOR MINIMUM RMSD OVER THE HEAVY ATOMS OF THE MEAN COORDINATE STRUCTURE. THE FIRST STRUCTURE IS THAT WITH THE LOWEST OVERALL ENERGY IN THE SIMPLIFIED ALL-HYDROGEN CHARMM FORCE FIELD AS IMPLEMENTED IN X-PLOR. | X-PLOR |
