CONFORMATION OF THE COMPLEX OF HUMAN INTERLEUKIN-2 FRAGMENT (66-72) WITH THE ANTI-INTERLEUKIN-2 MONOCLONAL-ANTIBODY

H-1-NMR spectra of the interleukin-2 synthetic fragment Ac-Leu66-Glu-G lu-Val-Leu-Asn-Leu72-OCH3 in the presence or absence of the monoclonal antibody were analysed. The data obtained are consistent with an exte nded unordered conformation of the free peptide. Measurements of NOESY cross-peak intensities allowed us to determine the spatial structure of the peptide bound to the antibody. The peptide has an amphiphilic s urface with hydrophobic and hydrophilic amino acid side chains cluster ed on the opposite sides of its alpha-helical-like structure. The hydr ophobic and hydrophilic clusters are located on the opposite sides of the bound peptide's surface. The hydrophobic side chains contact the a ntibody surface, while the hydrophilic ones are oriented into the solv ent (T. A. Balashova et al. (1991) Bioorgan. Khim. (USSR), v. 17, p. 1 470-1486). Hydrolysis of the methyl ester slowly occurs in the presenc e of the antibody. This process does not alter the conformation of the peptide bounded with the antibody, though decreases the peptide's aff inity to the antibody.