Three D structures of chitosan
| Autor: | Kozo Ogawa, Toshifumi Yui, Kenji Okuyama |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Models
Molecular Protein Conformation Stereochemistry Salt (chemistry) macromolecular substances Crystallography X-Ray Biochemistry Chitosan chemistry.chemical_compound Structural Biology Molecule Phenyl group Molecular Biology chemistry.chemical_classification Hydrogen bond technology industry and agriculture Water General Medicine equipment and supplies carbohydrates (lipids) Crystallography chemistry Intramolecular force Helix Hydrogen iodide Salts |
| Zdroj: | International Journal of Biological Macromolecules. 34:1-8 |
| ISSN: | 0141-8130 |
| DOI: | 10.1016/j.ijbiomac.2003.11.002 |
| Popis: | Crystal structures of two polymorphs of chitosan, tendon (hydrated) and annealed (anhydrous) polymorphs, have been reported. In both crystals, chitosan molecule takes up similar conformation (Type I form) to each other, an extended two-fold helix stabilized by intramolecular O3-O5 hydrogen bond, which is also similar to the conformation of chitin or cellulose. Three chitosan conformations other than Type I form have been found in the crystals of chitosan-acid salts. In the salts with acetic and some other acids, called Type II salts, chitosan molecule takes up a relaxed two-fold helix composed of asymmetric unit of tetrasaccharide. This conformation seems to be unstable because no strong intramolecular hydrogen bond like Type I form. Type II crystal changes to the annealed polymorph of chitosan by a spontaneous water-removing action of the acid. Chitosan molecule in its hydrogen iodide salt prepared at low temperature takes a 4/1 helix with asymmetric unit of disaccharide. The fourth chitosan conformation was found to be a 5/3 helix in chitosan salts with medical organic acids having phenyl group such as salicylic or gentisic acids. Similar conformation of chitosan molecule in the aspirin (acetylsalicylic acid) salt was suggested by a solid-sate NMR measurement. |
| Databáze: | OpenAIRE |
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