Determination of isoleucine side-chain conformations in ground and excited states of proteins from chemical shifts.
A simple method is presented for quantifying Ile chi(2) rotamer distributions in proteins based on the measurement of Ile (13)C(delta1) chemical shifts. The methodology is well suited for applications involving very high molecular weight protein complexes, where other NMR parameters such as side-chain scalar coupling constants that report on dihedral angles cannot be measured or for studies of invisible, excited protein states, where chemical shifts are obtained from analysis of CPMG relaxation dispersion profiles. The utility of the approach is demonstrated by an application to the folding reaction of a mutant Fyn SH3 domain, where Ile side-chain structure and dynamics of an on-folding pathway intermediate state are studied.
Hansen
D Flemming
DF
University of Toronto, Department of Molecular Genetics, 1 King's College Circle, Toronto, Ontario, Canada. flemming@pound.med.utoronto.ca
Neudecker
Philipp
P
Kay
Lewis E
LE
D007532:Isoleucine / Q000737:chemistry*; D008958:Models, Molecular; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D051076:Proto-Oncogene Proteins c-fyn / Q000737:chemistry / Q000235:genetics; D018909:src Homology Domains
D011506:Proteins; D007532:Isoleucine; D051076:Proto-Oncogene Proteins c-fyn