Synthesis and immunological evaluation of the conjugates composed from a muramyl peptide GMDP and tuftsin

The conjugates of a muramyl dipeptide analog GMDP (N-acetylglucosaminyl β1→4 N-acetylmuramyl-L-alanyl-D-isoglutamine) and tuftsin (Thr-Lys-Pro-Arg) were synthesized from unprotected GMDP by mixed anhydride procedure. The identity of the conjugates was confirmed by high resolution NMR and their immunomodulating properties were determined in various tests. It was found that the conjugate in which the GMDP carboxyl group forms an amide bond with the &-amino group of tuftsin lysyl residue exceeds GMDP in all the activities determined. Synergism of GMDP and tuftsin was found in phagocytosis stimulation assay.