Polarography of the oxytocin and vasopressin synthetic analogs

Abstract

Small changes in the molecules of the oxytocin and vasopressin synthetic analogs bring about considerable changes in their polarographic behaviour within the entire potential interval available (+0·5 to -2·0 V VS SCE). In the study of the polarographic activity of ten peptides we used classical, differential pulse and alternating current polarography and cyclic voltammetry. Liquid chromatographic separation studies of the peptides on the reverse phase complemented the electrochemical investigation. Hydrophobicity showed to be the parameter which decisively influences the polarographic behaviour of the studied peptides. Strong interaction of the SS and S-carba analogs with the electrode material (mercury) has been observed and surface activity of the SH-forms of the peptides at negative potentials has been confirmed. The importance of various functional groups in the peptide molecule for the catalytic activity in hydrogen evolution at negative potentials is discussed.