Purification of Synthetic Lipopeptide Conjugates by Liquid Chromatography

Conventional normal phase liquid chromatography (LC) was implemented for the purification of a synthetic lipid-peptide conjugate and its electrophilic lipid precursor. N-bromoacetic distearoylphosphatidylethanolamine (DSPE-COCH2Br) was extracted from the crude reaction mixture and purified in a single chromatographic step with a gradient of chloroform, methanol, and 50% aqueous acetic acid. This compound was covalently linked to Ser-Phe-Leu-Leu-Arg-Asn-(βAla)3-Tyr-NHCH2CH2SH, a hydrophilic decapeptide, and the conjugate was both extracted and purified in a single step by normal phase gradient LC using a hand-packed 3 mL Sep-Pak™ column. The eluent was a mixture of hexane, chloroform, 2-propanol, acetic acid, and water. Runs were monitored by thin layer chromatography and the plates developed with iodine and ninhydrin.