Premium
Dissecting the conformational determinants of chitosan and chitlac oligomers
Author(s) -
Esteban Carmen,
Donati Ivan,
Pantano Sergio,
Villegas Myriam,
Benegas Julio,
Paoletti Sergio
Publication year - 2018
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.23221
Subject(s) - glycosidic bond , chemistry , conformational isomerism , molecular dynamics , side chain , conformational change , crystallography , stereochemistry , computational chemistry , polymer , molecule , organic chemistry , enzyme
Chitosan and its highly hydrophilic 1‐deoxy‐lactit‐1‐yl derivative (Chitlac) are polysaccharides with increasing biomedical applications. Aimed to unravel their conformational properties we have performed a series of molecular dynamics simulations of Chitosan/Chitlac decamers, exploring different degrees of substitution (DS) of lactitol side chains. At low DS, two conformational regions with different populations are visited, while for DS ≥ 20% the oligomers remain mostly linear and only one main region of the glycosidic angles is sampled. These conformers are (locally) characterized by extended helical “propensities”. Helical conformations 3 2 and 2 1, by far the most abundant, only develop in the main region. The accessible conformational space is clearly enlarged at high ionic strength, evidencing also a new region accessible to the glycosidic angles, with short and frequent interchange between regions. Simulations of neutral decamers share these features, pointing to a central role of electrostatic repulsion between charged moieties. These interactions seem to determine the conformational behavior of the chitosan backbone, with no evident influence of H‐bond interactions. Finally, it is also shown that increasing temperature only slightly enlarges the available conformational space, but certainly without signs of a temperature‐induced conformational transition.