[Limited proteolysis of human leukocyte interferon-alpha2 and localization of the antigenic determinant binding the monoclonal antibodies].

Large peptide fragments of human leucocyte interferon-alpha 2 (INF-alpha 2) were obtained by limited proteolysis with trypsin, pepsin, thermolysine and Bacillus amyloliquefaciens intracellular serine proteinase. The ability of the fragments to bind murine monoclonal antibodies NK2 raised against INF-alpha 2 was studied by the immunoblotting technique. The region of sequence 110-149 is the most sensitive to proteolytic attack, being probably exposed on the surface of the INF-alpha 2 molecule. INF-alpha 2 fragments 1-139, 1-147, 1-149 are capable of binding antibodies, whereas fragments 1-109 and 1-112 do not bind antibodies NK2. A comparison of the primary structure of human leucocyte and murine leucocyte INF families in the region of sequence 110-139 and an analysis of the ability of human INF differing in amino acid sequences to bind antibodies NK2 demonstrated that the antigenic determinant for antibodies NK2 is the sequence Glu114-Asp115-Ser116-Ile117 of the INF-alpha 2 molecule.