Food & Soft Materials Science, Institute of Food, Nutrition & Health, Department of Health Sciences & Technology, ETH Zürich, Schmelzbergstraße 9, LFO E23, 8092 Zürich (Switzerland) http://www.ifnh.ethz.ch/lwm.
Angew Chem Int Ed Engl. 2014 May 19;53(21):5376-9. doi: 10.1002/anie.201402855. Epub 2014 Apr 16.
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.
通过原子力显微镜研究了单价盐存在下接近生理条件下阴离子卡拉胶多糖的结构构象。在高离子强度下，iota-卡拉胶发生螺旋-卷曲转变，而 lambda-卡拉胶则保持卷曲状态。聚合物统计分析表明，无规卷曲中的持久长度从 22.6±0.2 nm 增加到有序螺旋构象中的 26.4±0.2 nm，表明螺旋 iota-卡拉胶链的刚性增加。关于有序状态是单链还是双链存在的这个已经争论了几十年的问题，通过证明由单个聚合物链分子内形成的单体螺旋的存在，得到了明确的解决。
