About endothermic sorption of tyrosine on chitosan films

GARRO-MARTINEZ, JUAN C.; TAKARA, EDUARDO A.; TAKARA, EDUARDO A.; MARCHESE, JOSÉ; MARCHESE, JOSÉ; VEGA-HISSI, ESTEBAN G.; VEGA-HISSI, ESTEBAN G.; OCHOA, NELIO A.; OCHOA, NELIO A.; GARRO-MARTINEZ, JUAN C.

CARBOHYDRATE POLYMERS

ELSEVIER SCI LTD

Año: 2019 vol. 206 p. 57 - 64

0144-8617

Sorption of L- and D-Tyrosine (Tyr) from aqueous solutions on chiral membranes of chitosan (CH) was studied. Ahigh adsorption in the membrane, with a marked enantioselectivity to L-Tyr, was found. Computational calculationscarried out by docking and molecular dynamics (MD) showed a difference in the affinity of the enantiomersand two regions of adsorption in the polymer matrix. The interactions of the enantiomers with thepolymer matrix were studied by using FTIR, DRx, DSC and TG measurements. These results indicate that adsorptionof Tyr reduces the crystallinity of the membrane and generates a rearrangement of the chains, decreasingthe intercatenary spacing. Also, it was observed that the hydrated polymorph to anhydrous polymorphratio has changed during adsorption, that is, water bound to chitosan is also modified. The energy balance of thesystem hydrogen bonding, desolvation and the conformational changes resulted in a spontaneous and endothermicprocess.