SOLUTION STRUCTURES OF HUMAN TRANSFORMING GROWTH FACTOR-ALPHA DERIVED FROM H-1-NMR DATA

The 600-MHz 1H NMR spectrum of the des-Val-Val mutant of human transforming growth factor α (TGF-α) was reassigned at pH = 6.3. The conformation space of des-Val-Val TGF-α was explored by distance geometry embedding followed by restrained molecular dynamics refinement using NOE distance constraints and some torsion angle constraints derived from /-couplings. Over 80 long-range NOE constraints were found by completely assigning all resolved cross-peaks in the NOESY spectra. Low NOE constraint violations were observed in structures obtained with the following three different refinement procedures: interactive annealing in DSPACE, AMBER 3.0 restrained molecular dynamics, and dynamic simulated annealing in XPLOR. The segment from Phe 15 to Asp47 was found to be conformationally well-defined. Back-calculations of NOESY spectra were used to evaluate the quality of the structures. Our calculated structures resemble the ribbon diagram presentations that were recently reported by other groups. Several side-chain conformations appear to be well-defined as does the relative orientation of the C loop to the N-terminal half of the protein. © 1990, American Chemical Society. All rights reserved.