| AB INITIO-SIMULATED ANNEALING |
THE STRUCTURE WAS DETERMINED USING 756 DISTANCE RESTRAINTS, 52 DIHEDRAL ANGLE RESTRAINTS AND 22 HYDROGEN BOND RESTRAINTS. THE HYDROGEN BOND RESTRAINTS WERE USED ONLY IN THE LAST STEP OF REFINEMENT. 50 STRUCTURES WERE CALCULATED AND REFINED USING AB INITIO SIMULATED ANNEALING PROTOCOL FOR X-PLOR (1). ALL FORCE CONSTANTS AND POTENTIALS WERE SET TO THE DEFAULT (PROTOCOL) VALUES EXCEPT FOR THE VAN DER WAALS' RADII SCALE FACTOR ("REPEL"), WHICH WAS DECREASED TO 0.80 INSTEAD OF 0.75 DURING THE FINAL COOLING STAGES IN THE REFINEMENT. THIS RESULTS IN MORE REASONABLE BACKBONE CONFORMATION AND SOMEWHAT HIGHER X-PLOR TOTAL ENERGIES. CENTER AVERAGING PSEUDOATOM CORRECTION WAS USED FOR ALL DISTANCE RESTRAINT S(2). ON THE BASIS OF X-PLOR TOTAL ENERGY 42 LOWEST ENERGY STRUCTURES WERE SELECTED. |
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