Premium
Unravelling Secondary Structure Changes on Individual Anionic Polysaccharide Chains by Atomic Force Microscopy
Author(s) -
Schefer Larissa,
Adamcik Jozef,
Mezzenga Raffaele
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201402855
Subject(s) - random coil , chemistry , helix (gastropod) , crystallography , polymer , carrageenan , polysaccharide , persistence length , atomic force microscopy , rigidity (electromagnetism) , alpha helix , materials science , nanotechnology , organic chemistry , circular dichroism , ecology , biochemistry , snail , composite material , biology
The structural conformations of the anionic carrageenan polysaccharides in the presence of monovalent salt close to physiological conditions are studied by atomic force microscopy. Iota‐carrageenan undergoes a coil–helix transition at high ionic strength, whereas lambda‐carrageenan remains in the coiled state. Polymer statistical analysis reveals an increase in persistence length from 22.6±0.2 nm in the random coil, to 26.4±0.2 nm in the ordered helical conformation, indicating an increased rigidity of the helical iota‐carrageenan chains. The many decades‐long debated issue on whether the ordered state can exist as single or double helix, is conclusively resolved by demonstrating the existence of a unimeric helix formed intramolecularly by a single polymer chain.