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Molecular weight and chain conformation of amylopectin from rice starch
Author(s) -
Ma Zhaocheng,
Zhao Siming,
Cheng Ke,
Zhang Xufeng,
Xu Xiaojuan,
Zhang Lina
Publication year - 2007
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.26141
Subject(s) - amylopectin , radius of gyration , intrinsic viscosity , branching (polymer chemistry) , starch , chemistry , size exclusion chromatography , molar mass distribution , analytical chemistry (journal) , polymer , polysaccharide , amylose , hydrodynamic radius , crystallography , chromatography , organic chemistry , copolymer , enzyme
By using laser light scattering (LS) and size exclusion chromatography combined LS, we have investigated the molecular weight and chain conformation of amylopectin from rice of India (II‐b), japonica (IJ‐b), and glutinous (IG‐b) in dimethyl sulfoxide (DMSO) solution. The weight‐average molecular weight ( M w ) and radius of gyration (〈S 2 〉 ½ ) of amylopectin were determined to be 4.06 × 10 7 and 128.5 nm for India rice, 7.41 × 10 7 and 169.6 nm for japonica rice, 2.72 × 10 8 and 252.3 nm for glutinous rice, respectively. The 〈S 2 〉 ½ values were much lower than that of normal polymers, indicating a small molecular volume of amylopectin, as a result of highly branched structure. Ignoring the difference of degree of branching, approximated dependences of 〈S 2 〉 ½ and intrinsic viscosity ([η]) on M w for amylopectin in DMSO at 25°C were estimated to be 〈S 2 〉 ½ = 0.30 M w 0.35 (nm) and [η] = 0.331 M w 0.41 (mL g −1 ) in the M w range studied. Moreover, from the 〈S 2 〉 ½ values of numberless fractions obtained from many experimental points in the SEC chromatogram detected with LS, the dependence of 〈S 2 〉 ½ on M w for the II‐b sample was estimated also to be 〈S 2 〉 ½ = 0.34 M w 0.347 , coinciding with the above results. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007