PURIFICATION OF PROTECTED SYNTHETIC PEPTIDES BY PREPARATIVE HIGH PERFORMANCE LIQUID CHROMATOGRAPHY ON SILICA GEL 60

Abstract

A simple preparative system is described for rapid and efficient purification of protected synthetic peptides on a gram scale by high performance liquid chromatography on prepacked silica gel 60 columns. A variety of protected peptides up to tetradecapeptides were chromatographed at pressures of 50-150 psi and obtained in analytically pure form within 2-4 h. With such commonly used protecting groups as N-benzyloxycarbonyl (Z), N-2-(p-biphenylyl)-2-propyloxycarbonyl (Bpoc), N-t[tert]-butyloxycarbonyl (Boc), O- and S-t-butyl (But), and S-acetamidomethyl (Acm), compounds were sufficiently soluble in chloroform, alcohols, acetic acid or mixtures of these solvents for column loading. Dimethylformamide was also used as a solvent for loading. Solvent systems for column elution in isocratic, stepwise or gradient modes were composed of chloroform, isopropanol, ethanol or methanol and acetic acid in ratios that differed for each protected peptide depending on Rf values on TLC plates. A simple chromatograph is described which was self-assembled using standard instruments commonly in use in most laboratories. A shut-off valve was designed to prevent loss of material between fractions.