Use of capillary electrophoresis as a versatile tool to measure interaction constants between a KDR‐binding PEGylated lipopeptide and pegylated phospholipid micelles

Abstract

In the frame of our molecular imaging activities, a PEGylated lipopeptide has been developed as a specific ligand for the human vascular endothelial growth factor receptor 2, which is considered as one of the important molecular marker of angiogenesis. In this study, the potential of affinity capillary electrophoresis (ACE) is evaluated to measure the interactions of an active PEGylated lipopeptide, its hydrolysis product and its precursor consisting of a peptide structure with different micelles including Brij-35, Tween-20, and pegylated phospholipids. Given the amphiphilic structure of the PEGylated lipopeptide, a MEKC method allowing the simultaneous separation of the compounds of interest was set up, using low percentages of acetonitrile. Analytes were resolved using a BGE consisting of 100 mM borate buffer pH 9.0, 1 mM Brij, and 25% acetonitrile. Optimized conditions were then used to perform ACE experiments. The affinity constants of the analytes with the micelles were calculated on the basis of their mobility decrease when surfactant concentration increased in the electrolyte. The use of different linearization models to estimate affinity constants was discussed and comparison of different surfactants was reported. PEGylated lipopeptide interacted more strongly with pegylated phospholipid micelles than with Brij-35 or Tween-20. Moreover, it is likely that the chemical structure of the compounds, and particularly the lipidic part of the molecules, significantly affects the interaction with micelles. In conclusion, the ACE method can be readily applied to investigate interactions of our targeting lipopeptides with various micelles currently used for the preparation of pharmaceutical vehicles.

Recent developments in capillary and microchip electroseparations of peptides (2013–middle 2015)

“…peptides with blocked or derivatized N‐ and C‐terminus and other ionogenic groups of peptide molecules, and/or for separation of peptides with identical or very close charge/mass ratio but differing in their hydrophobicity. Two examples of MEKC application to investigation of peptide and peptidomimetic complexes, particularly to the study of interactions of PEGylated lipopeptide with different micelles and to estimation of binding constant of the complexes of pyroglutamic acid derivatives with negatively charged CDs , are described in more detail in the below Section .…”

“…The strength of the interactions of an active PEGylated lipopeptide, its hydrolytic product and its precursor consisting of a peptide structure with different micelles, e.g. Brij‐35, Tween 20, and pegylated phospholipids was investigated by affinity MEKC method using 100 mM borate buffer, pH 9.1, 25% v/v ACN as BGE, and variable concentrations of Brij or of other surfactants or phospholipids as pseudostationary phases . The binding constants of the analytes with the micelles were calculated on the basis of their mobility decrease with increasing concentration of surfactants in the BGE.…”