Structure
of starches extracted from near-isogenic wheat lines |
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Authors: | S S Kozlov A V Krivandin Olga V Shatalova T Noda E Bertoft J Fornal V P Yuryev |
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Institution: | (1) Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia, 119991, 4, str. Kosygina;(2) Department of Upland Agriculture, National Agricultural Research Center for Hokkaido Region, NARO Shinsei, Memuro Kasai, Hokkaido Japan, 082-0071;(3) Department of Biochemistry and Pharmacy, Abo Akademi University, BioCity, Turku, Finland, P.O. Box 66, 20521;(4) Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland, 10-747, 10 Tuwina Str. |
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Abstract: | High-sensitivity differential
scanning calorimetry (HSDSC) and small-angle X-ray scattering (SAXS) were
used to investigate the structural characteristics of starch granules with
different amylose content extracted from near-isogenic wheat lines with different
combinations of active granule-bound starch synthase (GBSS I) isoforms. Paracrystalline
diffraction model, ‘two-state’ model of starch melting and other
physico-chemical approaches were used to estimate the sizes of amylopectin
clusters, the thicknesses of crystalline lamellae and the structure of amylopectin
defects for investigated wheat starches.
The joint analysis of
SAXS and DSC data has shown that the size of amylopectin cluster, the thickness
of crystalline lamellae and the structure of amylopectin defects do not depend
on the differences in combinations of active GBSS I isozymes. The data obtained
supposed that the amylopectin cluster size and the thickness of crystalline
lamellae are, generally, the universal structural parameters for wheat starches.
Additionally, the data obtained suggest that increase of amylose content is
accompanied by accumulation of both amylose tie-chains, located as defects
in crystalline lamellae, and amylose chains oriented transversely to the lamella
stack within amorphous lamellae. Disordered ends of amylopectin double helices
and/or pre-existing double helices not participating in formation of crystals
are considered as amylopectin defects arranged in crystalline lamellae. The
relationship between structure of wheat starches extracted from near-isogenic
lines and their thermodynamic properties was recognized. |
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Keywords: | amylose and amylopectin localization cluster and lamellar structure GBSS I HSDSC native and annealed wheat starches SAXS |
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