Peptides, by nature, are composed of amino acids with potentially ionizable chemical moieties. The ionization state of any of these moieties can significantly impact the peptide’s chromatographic behavior, both in terms of peak shape and retention by the solid support. Peptide purification by reversed-phase chromatography, however, almost exclusively includes an acidic additive to the mobile phase solvents, maintaining the solution at a pH of 2-3 throughout the purification cycle. But have you ever considered trying an alternative additive in the mobile phase to improve your purification results?
In the following post I discuss the impact of mobile phase pH in the purification of oxytocin (CYIQNCPLG-NH2), a 9-amino acid peptide that requires disulfide bond-mediated cyclization for its biological activity.
Continue reading Peptide purification improvements with flash column chromatography by modulating mobile phase pH
When it comes to synthesizing a peptide, the first thing that comes to mind is the number of stoichiometric equivalents to use. Sometimes that number is as few as 1.5, sometimes it’s as high as 20!
But have you ever thought about the liquid volume that contain those molecules and how that might affect the success of your coupling reaction? In this post I will discuss the impact of amino acid concentration in the overall success of solid phase peptide synthesis.
Continue reading Does amino acid concentration really matter during peptide synthesis?