146D

SOLUTION STRUCTURE OF THE MITHRAMYCIN DIMER-DNA COMPLEX


SOLUTION NMR
NMR Refinement
MethodDetailsSoftware
MOLECULAR DYNAMICS, MATRIX RELAXATIONTWO STARTING MODELS WERE OBTAINED BY DOCKING THE MG2+ COORDINATED MITHRAMYCIN DIMER IN THE MINOR GROOVE OF A AND B FORM D(TCGCGA) DUPLEX. THESE MODELS WERE SUBSEQUENTLY REFINED BY DISTANCE RESTRAINED MOLECULAR DYNAMICS USING A SET OF INTER-PROTON DISTANCE RESTRAINTS DERIVED FROM THE NMR DATA. THE TWO DISTANCE-REFINED STRUCTURES WERE REFINED FURTHER USING RELAXATION-MATRIX BASED NOE INTENSITY-RESTRAINED MOLECULAR DYNAMICS. THE FINAL TWO STRUCTURES WERE OBTAINED BY TAKING THE AVERAGE COORDINATES OF THE LAST 1 PS OF THE DYNAMICS DURING RELAXATION MATRIX REFINEMENT AND MINIMIZED. THE R VALUE WAS USED TO REFINE THE STRUCTURE DURING RELAXATION MATRIX REFINEMENT. THE R FACTOR AND THE RMS DEVIATIONS FROM IDEAL GEOMETRY FOR THE TWO FINAL STRUCTURES ARE: MODEL 1 MODEL 2 R FACTOR 0.146 0.136 BOND (ANGSTROMS) 0.016 0.013 ANGLES (DEGREES) 3.410 3.369. THE STRUCTURE EXHIBITS APPROXIMATE TWO-FOLD SYMMETRY, PERPENDICULAR TO THE HELICAL AXIS AND PASSING THROUGH THE MAGNESIUM IN THE COMPLEX. THE TRANSFORMATION PRESENTED ON *MTRIX 1* RECORDS BELOW WILL YIELD APPROXIMATE COORDINATES FOR CHAIN B OF MODEL 1 WHEN APPLIED TO CHAIN A OF MODEL 1. THE TRANSFORMATION PRESENTED ON *MTRIX 2* RECORDS BELOW WILL YIELD APPROXIMATE COORDINATES FOR CHAIN B OF MODEL 2 WHEN APPLIED TO CHAIN A OF MODEL 2.X-PLOR
NMR Ensemble Information
Conformer Selection Criteriaall calculated structures submitted
Conformers Calculated Total Number2
Conformers Submitted Total Number2
Additional NMR Experimental Information
DetailsTHE HYDROXYL PROTONS IN THE RELAXATION MATRIX REFINED STRUCTURES ARE NOT WELL DETERMINED. THE HYDROPHILIC SIDE CHAIN, THE B SUGAR RESIDUE DDA 1 AND DDA 7, AND RESIDUES T 1 AND C 2 ARE UNDETERMINED.
Computation: NMR Software
#ClassificationVersionSoftware NameAuthor
1refinementX-PLOR2.1Brunger