Synthesis of an IgG fragment decapeptide exhibiting phagocytosis stimulating activity of polymorphonuclear leucocytes

Abstract
Fragment 335-344 of human IgG was synthesized stepwise, using active esters of N-protected amino acids and benzotriazolyloxytris (dimethylamino)phosphonium hexafluorophosphate for coupling. This fragment could be liberated from the carrier molecule by the 2 specific enzymes responsible for the release of tuftsin from the same carrier molecule: tuftsin endocarboxy-peptidase cleaves at the Arg.sbd.Glu bond and leukokininase at the Lys.sbd.Thr bond. This decapeptide fragment. Thr-Ile-Ser-Lys-Ala-Lys-Gly-Gln-Pro-Arg showed significant activity in stimulating phagocytosis of human polymorphonuclear leukocytes.