C(6)-Oxidation and C(5)-Epimerization of Locust Bean Galactomannan Studied by High Field NMR and Circular Dichroism

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• 作者：Mariella Dentini ; Daniele Caucci ; Andrea Barbetta ; Vittorio Crescenzi ; Gudmund Skjå ; k-Br&aelig ; k ; Donatella Capitani ; Luisa Mannina ; and Sté ; phane Viel
• 刊名：Biomacromolecules
• 出版年：2006
• 出版时间：January 2006
• 年：2006
• 卷：7
• 期：1
• 页码：54 - 63
• 全文大小：382K
• 年卷期：v.7,no.1(January 2006)
• ISSN：1526-4602

文摘

Galactose depleted locust bean gum was selectively oxidized in C(6) position and epimerized with mannuronanC(5)-epimerases to obtain the corresponding artificial uronanes. These new pseudo-alginates were characterizedby NMR spectroscopy and circular dichroism (CD). Specifically, 1D and 2D NMR techniques allowed the degreeof epimerization, the distribution of mannuronic and guluronic acid residues in the polysaccharidic chain, and theaverage G block length to be determined. In addition, NMR diffusion experiments showed that the epimerizationreaction did not significantly degrade the polysaccharidic chains. Circular dichroism was used to investigate thekinetics of the epimerization reaction and to evidence the specific interaction between the epimerized locust beansamples with Ca(II) ions in dilute solution. All of the samples considered in this study form wall to wall gels inconcentrated polymer solutions.