Sorbtion of threonilthreonine and threonine by ion exchange sorbents

Abstract

Sorbtion of threonilthreonine dipeptide (Thr-Thr) and its monomeric amino acid threonine (Thr) on
ion exchange sorbents from individual and two-component solutions was studied in order to obtain data that
can be used for the development of their separation method.
It was found that the sorbtion of Thr-Thr on AV-17 and KU-2-8 is higher than that of Thr. In case of
KU-2-8 with the increasing equilibrium concentration (>20 mmol/l) the content of dipeptide in the sorbent
phase remains constant, in case of threonine - extra-equivalent sorbtion is observed. IR-spectroscopic studies
of KU-2-8, comprising of Thr, showed the presence of intense absorption bands typical for dissociated (1600
cm-1) and undissociated carboxyl group (1738 cm-1), which may indicate the sorbat-sorbat interaction. It was
shown that in case of Thr-Thr sorption at KU-2-8 there are no absorption bands of carboxylate-ion.
Sorbtion of Thr-Thr and Thr by anion exchanger AV-17 from the two-component solutions with different
molar ratio of the components was studied. There was revealed an increase of dipeptide sorbtion in the
presence of Thr and inhibition of amino acids sorbtion compared to the sorbtion from individual solutions.
Separation coefficients were calculated. The data obtained indicate the possibility of Thr-Thr and Thr separation
from their mixtures. It can be useful for the purification of the dipeptide from the amino acid impurities.