Formation of the poly(L-lysine) complex with pectin of various esterification degree

Abstract

The circular dichroic (CD) measurement was chosen the tool to investigate the complex formation of poly(L-lysine) with potassium pectate or pectinate of various esterification degree (E). The polycation-polyanion (pectate, E 0%) 1 : 1 complex was quantitatively formed by an electrostatic interaction independently upon the excess of either component. The partial esterification of pectin resulted in a decrease of complex formation; this drop is at a 20% esterification degree low, at higher esterification degrees (46% and 64%) considerable, and at an esterification degree 86% the complex has not been formed at all. The polypeptide chain was present in the complex in an α-helical arrangement characterized by the CD spectrum; the potential spatial arrangements of the complex were proposed. The α-helical polypeptide component constitutes a core surrounded by a superstructure of D-galacturonan chains.