Direct Structure Refinement against Residual Dipolar Couplings in the Presence of Rhombicity of Unknown Magnitude

✍ Scribed by G.Marius Clore; Angela M. Gronenborn; Nico Tjandra

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 117 KB
• Volume: 131
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1997.1345

✦ Synopsis

Residual dipolar couplings arising from small degrees of aligntein-DNA complexes, as opposed to proteins alone, is simment of molecules in a magnetic field provide unique long-range plified as the magnetic susceptibility tensor is dominated by structural information. The potential of this approach for structure the DNA bases which are stacked on top of one another, refinement has recently been demonstrated for a protein-DNA resulting in axial symmetry (16). In the majority of cases, complex in which the magnetic susceptibility tensor was axially however, axial symmetry cannot be assumed a priori. This symmetric. For most macromolecules and macromolecular comis particularly so when a dilute aqueous liquid crystalline plexes, however, axial symmetry cannot be assumed. Moreover, medium of oriented bicelles is used to produce moderate the presence of significant rhombicity will clearly affect the accudegrees of alignment of biomolecules in a magnetic field racy of the resulting coordinates. In this Communication we prewhile retaining the sensitivity, simplicity, and resolution of sent a simple calculational strategy that makes use of simulated spectra recorded in an isotropic medium (17). Since the annealing refinement against the residual dipolar couplings in combination with a grid search, to simultaneously refine the struc-assumption of axial symmetry in the presence of significant tures and ascertain the magnitude of the axial and rhombic comporhombicity will clearly affect the accuracy of the resulting nents of the tensor.

coordinates, it is important to devise a simple calculational Key Words: residual dipolar couplings; rhombicity; solution strategy for determining the degree of rhombicity from the NMR structure determination; long-range restraints; simulated experimental residual dipolar coupling data without referannealing.