Comparative study on molecular size, multi-branched structure, and chain conformation of amylopectins from three rice cultivars
| Autor: | Siming Zhao, Qilin Huang, Ting Hu |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | Starch - Stärke. 66:841-848 |
| ISSN: | 1521-379X 0038-9056 |
| DOI: | 10.1002/star.201400013 |
| Popis: | Molecular size, multi-branched structure, and chain conformation of amylopectins from indica (Ir-AP), japonica (Jr-AP), and glutinous rice (Gr-AP) were investigated by laser light scattering (LLS), isoamylase debranching with gel permeation chromatography (GPC) separation and viscometry. The weight-average molecular weight (Mw), radius of gyration (〈S2〉1/2), and intrinsic viscosities ([η]) in DMSO at 25°C were measured separately for Ir-AP (4.72 ± 0.15 × 107, 163.70 ± 2.1 nm and 456.47 mL/g), Jr-AP (6.61 ± 0.41 × 107, 170.40 ± 2.6 nm and 569.68 mL/g), and Gr-AP (2.35 ± 0.34 × 108, 253.20 ± 16.3 nm and 926.08 mL/g). The Gr-AP showed a dramatically lower overlapping concentration (c* = 1/(A2Mw), 1.40 × 10−4 g/mL) than Ir-AP and Jr-AP (1.13 × 10−3 g/mL and 1.04 × 10−3 g/mL), indicating that the first had more entanglements between macromolecular chains than the latter two. Based on the cluster model and A:B chain ratios, the Gr-AP had more branched chains and longer internal-chains than Ir-AP and Jr-AP. In view of polymer solution theory, the molecular parameters of ρ (viscometric radius Rη/〈S2〉1/2) and σ (A2Mw/[η]) revealed that Ir-AP, Jr-AP, and Gr-AP existed as hyperbranched chains occupying a spherical volume and the first two presented a star-like branched conformation in DMSO. This research provides the insights into multi-branched structure and chain conformation of AP as well as a theoretical basis for interpretation of AP functional properties associated with their molecular structure. |
| Databáze: | OpenAIRE |
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