H + Ion Equilibria in Solutions of Copolypeptides of L -Lysine and L -Aspartic Acid and of L -Lysine and L -Glutamic Acid

pH and conductometric titration curves of copolypeptides containing L-lysine and either L-glutamic acid or L-aspartic acid residues have provided necessary evidence to believe that in the copolypeptides the zwitterion formation is complete at the isoionic point. The amounts of acid/alkali used up at the final inflexion/break in the titration curves agreed with the analytically determined quantity of basic/acid groups in the copolypeptides. Besides, the titration curves showed additional inflexions/breaks which distinguished between the various kinds of acid/basic groups present.