Solution structure of murine epidermal growth factor: determination of the polypeptide backbone chain-fold by nuclear...

The polypeptide backbone fold in the solution structure of murine epidermal growth factor has been determined by nuclear magnetic resonance spectroscopy and distance geometry calculations. The results are based on nearly complete sequence-specific resonance assignments and on 333 distance and dihedral-angle constraints; these were determined from nuclear Overhauser effect measurements, identification of hydrogen-bonded amide protons, the known locations of disulfide bonds, and backbone vicinal spin-spin coupling constants. The polypeptide chain of the protein is arranged into two distinct domains. The structures of these domains were determined independently in separate calculations and then combined to obtain an overall view of the protein. The backbone fold thus determined includes the regular backbone structure elements that were previously identified using different techniques for the analysis of the nuclear magnetic resonance data. The distance geometry calculations also provided additional details about the conformations of bends and loops and about the twists of the beta-sheets.