Structural study of amylose polymorphs by cross-polarization-magic-angle spinning, 13C-N.M.R. spectroscopy

✍ Scribed by Fumitaka Horn; Hiroyuki Yamamoto; Asako Hirai; Ryozo Kitamaru

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 827 KB
• Volume: 160
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(87)80301-4

✦ Synopsis

C.p.-m.a.s. 13C-n.m.r. spectra and 13C spin-lattice relaxation times (I;) at room temperature have been measured for recrystallized samples of different polymorphs of amylose. Although the spectra of A-and B-amyloses in the dry state are very broad and ahnost structureless, the respective resonance lines of the samples soaked in H,O narrow markedly, and tine splittings can be observed in the C-l lines, namely, a triplet for the A-type crystal form and a doublet for the B-type crystal form. These multiplicities had already been reported for native A-and Bstarches, but the resolution is much higher for the recrystallized samples. In contrast, all resonance lines are composed of single signals for the hydrated and anhydrous V-amyloses, without any significant effect of hydration. It is also found that 13C T1 values of the crystalline components of amyloses are much shorter than those of celluloses. This suggests that the enhanced torsional motion about the cr-D-(l-4)-glycosyl linkages is allowable for amyloses, even in the crystalline region, because of the flexible, helical structure.