X-ray structure of the cyclomaltohexaicosaose triiodide inclusion complex provides a model for amylose–iodine at atomic resolution
| Autor: | George M. Sheldrick, H Welfle, Katrin Geßler, Olaf Nimz, Wolfram Saenger, Isabel Usón, S Laettig |
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| Rok vydání: | 2003 |
| Předmět: |
Models
Molecular Molecular Sequence Data Iodine Compounds chemistry.chemical_element Crystallography X-Ray 010402 general chemistry Antiparallel (biochemistry) Iodine 01 natural sciences Biochemistry Analytical Chemistry symbols.namesake chemistry.chemical_compound Amylose Carbohydrate Conformation Molecule Triiodide Cyclodextrins 010405 organic chemistry Organic Chemistry X-ray General Medicine 0104 chemical sciences Oxygen Crystallography Carbohydrate Sequence chemistry symbols van der Waals force Raman spectroscopy |
| Zdroj: | Carbohydrate Research. 338:977-986 |
| ISSN: | 0008-6215 |
| DOI: | 10.1016/s0008-6215(03)00016-8 |
| Popis: | Cyclomaltohexaicosaose (CA26) is folded into two 1(2)/(3) turns long V-helices that are oriented antiparallel. Crystals of complexes of CA26 with NH(4)I(3) and Ba(I(3))(2) are brown and X-ray analyses show that I(3)(-) units are located in the approximately 5 A wide central channels of the V-helices. In the complex with NH(4)I(3), two CA26 molecules are stacked to form 2 x 1(2)/(3) turns long channels harbouring 3 I(3)(-) at 3.66-3.85 A inter I(3)(-) distance (shorter than van der Waals distance, 4.3 A), whereas in the Ba(I(3))(2) complex, CA26 are not stacked and only one I(3)(-) each fills the V-helices. Glucose...I contacts are formed with C5-H, C3-H, C6-H and (at the ends of the V-helices) with O6 in (+) gauche orientation. By contrast, O2, O3, O4 and O6 in the preferred (-) gauche orientation do not interact with I because these distances are/=4.01 A and exceed the van der Waals I...O sum of radii by about 0.5 A except for one O2...I distance of 3.68 A near the end of one V-helix. Raman spectra indicate that the complexes share the presence of I(3)(-) with blue amylose-iodine. |
| Databáze: | OpenAIRE |
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