Syntheses of scotophobin analogs

The solid phase synthesis of two sootophobin analogs, 2-Asn-5-Gln-11-Gln-sootophcbin and 2-Asp-5-Gln-11-Gln-scotophobin was carried out. The peptides were cleaved from the resin by ammonolysis, since the C-terminal amino acid of scotophobin is amidated. In the case of 2-Asp-5-Gln-11-Gln-scotophobin, a direct arononolysis using liquid ammonia in EMF was successfully applied. The 2-Asn-analog was cleaved from the resin according to the conventional method by transesterification with MeOH/NEt[lowered 3], followed by ammonolysis in methanolic armonia. The biological activity of 2-Asn-5-Gln-11-Gln-scotophobin was 10 - 12%; the material obtained in the second synthesis had the same biological activity as natural scotophobin, also its chromatographic data were similar to those obtained from the natural peptide. The classical synthesis of 2-Asp-5-Gln-11-Gln-scotophobin was carried out via the fragmentation technique. The heptapeptide 1-8 was obtained by the condensation of the tetrapeptide 1-4 with the tripeptide 5-7. The octapeptide 8-15 was synthesized from three fragments. The two tripeptides 8-10 and 11-13 were coupled to the hexapeptide, which then was condensed with the dipeptide 14-15 to yield the octapeptide. The pentadecapeptide was obtained by the condensation of the heptapeptide and the octapeptide.