We propose to attempt to identify the amino acid sidechains of the specific iron and anion binding sites of the proteins called siderophilins, esp, transferrin and ovotranferrin (conalbumin). Furthermore, we seek to identify those amino acids which serve as ligands to the iron and anions and to determine the spatial disposition of the binding site amino acids. The major investigational tool will be high resolution nuclear magnetic resonance. In order to simplify interpretation of the spectral data, N- and C-terminal """"""""half-molecules"""""""", of the siderophilins, each with its attendant binding site will be studied. In the case of ovotransferrin, protein with selectively deuterrated or 13C-enriched amino acids will be produced by feeding birds a defined diet containing the modified amino acids. These substitutions will substantially simplify the nmr spectra and therefore their interpretation. Differences in the binding sites will be sought.
