Purification of a synthetic myristylated peptide by counter-current chromatography

Separations of hydrophobic synthetic peptides in counter-current chromatography

Synthetic peptides with many aromatic, aliphatic and especially acidic amino acid residues are not very soluble and require strong solvents for useful partitioning. A chloroform-methanol-acidic solvent system fractionates neutral and basically charged 26-mers to provide high yields. An insoluble 15-mer with 5 Trp residues and 60% overall hydrophobic amino acid content was purified in pyridine-acetic acid and in another basic t-butyl methyl ether-n-butanol-acetonitrile solvent system with high recovery. Two instruments were used, the eccentric-multi-layer hybrid coil planet centrifuge and the new spiral disk planet centrifuge that were able to retain the stationary phase of these solvent systems, some of which have low interfacial tension.

Inhibitory cyclic analogues and chlorambucil derivatives of bombesin-like peptides

Analogues of the amphibian neuropeptide, bombesin, and of the mammalian homologue, gastrin-releasing peptide, have been synthesized and their biological activity studied in small cell lung carcinoma and rat pancreatic acinar cells. The compounds are truncated sequences of the active tetradecapeptide BN(1-14) or GRP(20-27). Peptides were cyclized between position 5 or 7 and the carboxyl end of the des-Met14 fragment with D and L Ala11 and Lys5 substitutions, as well as various N-terminal groups attached. The smallest cyclic peptide, BN(7-13), bound to SCLC membranes with microM potency and inhibited BN stimulation of intracellular Ca++ levels. The most potent inhibitor is N-chloroambucil-[His7,D-Ala11]BN(7-13)ethyl ester, which antagonized BN function in SCLC and acinar cells with nM potency and also inhibited clonal growth of carcinoma cell lines.

Recent advances in counter-current chromatography

During the past several years, counter-current chromatography (CCC) technology has been advanced to cover a broad spectrum of applications, from large-scale preparative to analytical-scale separations. These advances include liquid-liquid dual CCC, foam CCC and partition of macromolecules with aqueous-aqueous polymer phase systems. For these developments the synchronous coil planet centrifuge scheme has been used, which relies on a relatively simple mechanical design. Future developments in CCC may be focused on the improvement of the more intricate non-synchronous coil planet centrifuge scheme which has a greater potential for the separation of biopolymers and cell particles.