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“The water-soluble chitosan derivative grafted with short

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“The water-soluble chitosan derivative grafted with short amylose chains (Chit-Amy-Ill) was synthesized through the phosphorylase-catalyzed enzymatic polymerization, following that the chitosan was grafted with maltoheptaose residues by reductive

amination. The chemical structures were characterized by FTIR, (1)H NMR, Raman, XRD and static light scattering analyses. The results indicated that the amylose chains were conjugated with the chitosan backbone through the reductive Shiff base bonds (-CH-NH-), and the polymerization degree of the grafted amylose chains was about 25. The dispersion stability of single-walled carbon nanotubes (SWNTs) in water was improved through the complexation of Chit-Amy-III derivatives with SWNTs. Raman, XRD and TEM analyses confirmed that the resultant selleck inhibitor Chit-Amy-SWNTs complex was formed by the wrapping of the Chit-Amy-III derivative around the SWNTs. The results

of electrochemical analysis indicated that the Chit-Amy-SWNTs complex modified electrode displayed excellent electron conductivity and electrocatalytic activity on H(2)O(2). (C) 2011 Elsevier Ltd. All rights reserved.”
“Highly branched alpha-glucan molecules exhibit low digestibility for alpha-amylase and glucoamylase, and abundant in alpha-(1 -> 3)-, alpha-(1 ->-6)-glucosidic linkages and alpha-(1 -> 6)-linked branch points where another glucosyl chain is initiated through art alpha-(1 -> Bucladesine 3)-linkage. From a culture supernatant of Paenibacillus sp. PP710, we purified alpha-glucosidase (AGL) and alpha-amylase (AMY), which were involved in the production of highly branched alpha-glucan from maltodextrin. AGL catalyzed the transglucosylation reaction of a glucosyl residue to a nonreducing-end glucosyl residue by alpha-1,6-, alpha-1,4-, and

alpha-1,3-linkages. AMY catalyzed the hydrolysis of the alpha-1,4-linkage and the intermolecular or intramolecular transfer of maltooligosaccharide like cyclodextrin glucanotransferase (CGTase). It. also catalyzed the transfer of an alpha-1,4-glucosyl chain to a C3- or C4-hydroxyl group in the alpha-1,4- or alpha-1,6-linked nonreducing-end residue Curaxin 137 HCl or the alpha-1,6-linked residue located in the other chains. Hence AMY was regarded as a novel enzyme. We think that the mechanism of formation of highly branched alpha-glucan from maltodextrin is as follows: alpha-1,6- and alpha-1,3-linked residues are generated by the transglucosylation of AGL at the nonreducing ends of glucosyl chains. Then AMY catalyzes the transfer of alpha-1,4-chains to C3- or C4-hydroxyl groups in the alpha-1,4- or alpha-1,6-linked residues generated by AGL. Thus the concerted reactions of both AGL and AMY are necessary to produce the highly branched a-glucan from maltodextrin.

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