INTERACTION OF ALGINATES AND PECTINS WITH CATIONIC POLYPEPTIDES

The interactions of alginates of various compositions and of pectins with basic polypeptides, namely, poly(l-lysine) and poly(Lys-Ala-Ala), have been studied by means of circular dichroism. The complexation efficiency of both types of anionic polysaccharides were compared and quantified on the basis of the extent of the induced α-helical conformation of the polypeptide. The alginate with a high content of guluronic acid (∼ 75%) did not interact with poly(l-lysine). Pectins and alginates interacted with poly(Lys-Ala-Ala) rather intensively. The difference in efficiency of interaction of l-guluronan and d-galacturonan with poly(l-lysine) results from the difference in the conformational flexibility of their polyanionic chains in solution. l-Guluronan maintains the rigid two-fold symmetry in solution, and d-galacturonan is conformationally adaptable in the course of interaction. © 1990.