Proton-NMR assignment and secondary structural elements of human transforming growth factor

Abstract
The 1H NMR spectrum of human transforming growth factor .alpha. (hTGF-.alpha.) has been completely assigned, and secondary structural elements have been identified as a preliminary step in determining the structure of this protein by distance geometry methods. Many of these structural elements closely correspond to those previously found in a truncated human EGF [Cooke et al. (1987) Nature (London) 327, 339-341] and murine EGF [Montelione et al. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 5226-5230]. These include the presence of an antiparallel .beta.-sheet between residues G19 and C34 with a type I .beta.-turn at V25-D28, a type II .beta.-turn at H35-Y38, and another short .beta.-sheet between residues Y38-V39 and H45-A46.