A synthetic peptide corresponding to the 550-585 region of alpha-dystroglycan binds beta-dystroglycan as revealed by NMR spectroscopy

We have probed the binding of a synthetic peptide corresponding to the regi on 550-585 of the alpha subunit of dystroglycan with a recombinant protein fragment corresponding to the N-terminal extracellular region of beta -dyst roglycan (654-750), using NMR in solution. In a 30:1 molar ratio, the pepti de binds to the recombinant protein fragment in the fast/intermediate excha nge regime, By monitoring the peptide intraresidue HN-H alpha peak volumes of the 2D TOCSY NMR spectra, both in the absence and in the presence of the recombinant fragment, we determined the differential binding affinities of each amino acid. We found that the residues in the region 550-565 (SWVQFNS NSQLMYGLP) are more influenced by the presence of the protein, whereas the C-terminal portion is marginally involved. These NMR results hale been conf irmed by solid-phase binding assays. (C) 2001 Federation of European Bioche mical Societies. Published by Elsevier Science B.V. All rights reserved.