[Conformation of fragment 66-72 of interleukin-2 complexed with a monoclonal antibody to interleukin-2]. / Konformatsiia fragmenta 66-72 interleikina-2 v komplekse s monoklonal'nym antitelom k interleikinu-2.

ABSTRACT

1H-NMR spectra of the interleukin-2 synthetic fragment Ac-Leu66-Glu-Glu-Val-Leu-Asn-Leu72-OCH3 in the presence or absence of the monoclonal antibody were analysed. The data obtained are consistent with an extended 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 surface with hydrophobic and hydrophilic amino acid side chains clustered on the opposite sides of its alpha-helical-like structure. The hydrophobic and hydrophilic clusters are located on the opposite sides of the bound peptide's surface. The hydrophobic side chains contact the antibody surface, while the hydrophilic ones are oriented into the solvent (T. A. Balashova et al. (1991) Bioorgan. Khim. (USSR), v. 17, p. 1470-1486). Hydrolysis of the methyl ester slowly ocurs in the presence of the antibody. This process does not alter the conformation of the peptide bounded with the antibody, though decreases the peptide's affinity to the antibody.