Backbone Conformational Constraints in a Microcrystalline U-~(15)N-Labeled Protein by 3D Dipolar-Shift Solid-State NMR Spectroscopy

摘要

Structural studies of uniformly labeled proteins by magic-angle spinning (MAS) NMR have rapidly matured in recent years.Site-specific chemical shifts of several proteins have been assigned,and structures have been determined from 2D or 3D data sets containing internuclear distance information.Thus far,MAS NMR structures have a relatively low resolution in comparison to high-quality solution NMR or crystal structures,for two principal reasons: (1) the distance constraints extracted from multidimensional protein spectra are not yet as precise as those measured in small peptides and model compounds; (2) the number of constraints per residue is typically much less than that in solution NMR protein studies.These problems continue to be addressed by a variety of approaches,as recently reviewed.