SIDE-REACTIONS IN PEPTIDE-SYNTHESIS .2. FORMATION OF BY-PRODUCTS IN THE LARGE-SCALE SYNTHESIS OF THF-GAMMA-2 BY SOLUTION SYNTHESIS

The impurities which formed in the large-scale synthesis of THF-gamma 2, an immunomodulatory peptide of formula H-Leu-Glu-Asp-Gly-Pro-Lys-Ph e-Leu-OH, were identified by a combination of analytical methods, and their structure confirmed by synthesis. Most impurities originated fro m side-reactions involving the aspartyl residue (cyclization, beta-asp artyl formation and cleavage). Based on this knowledge, modifications were introduced into the work up and the purification procedure which resulted in a very pure final product (> 99% by RP-HPLC). (C) Munksgaa rd 1994.