Phosphate Positioning and Availability in the Starch Granule Matrix as Studied by EPR

Cu2+ was introduced as an EPR probe into the starch granules isolated from different starch crop genotypes including transgenically modified potatoes generated for extreme amylose and starch phosphate monoester concentrations. Several discrete copper adducts bound to the starch matrix with different...

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Bibliographic Details
Published in:Biomacromolecules 2006-03, Vol.7 (3), p.965-974
Main Authors: Blennow, Andreas, Houborg, Karen, Andersson, Roger, Bidzińska, Ewa, Dyrek, Krystyna, Łabanowska, Maria
Format: Article
Language:English
Subjects:
Amylose - metabolism
Applied sciences
Calorimetry, Differential Scanning
Copper - chemistry
Electron Spin Resonance Spectroscopy - methods
Esters - chemistry
Exact sciences and technology
Genotype
Ions
Magnetics
Molecular Conformation
Natural polymers
Phosphates - chemistry
Physicochemistry of polymers
Plants, Genetically Modified
Solanum tuberosum - metabolism
Starch - chemistry
Starch and polysaccharides
Water - chemistry
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Summary:Cu2+ was introduced as an EPR probe into the starch granules isolated from different starch crop genotypes including transgenically modified potatoes generated for extreme amylose and starch phosphate monoester concentrations. Several discrete copper adducts bound to the starch matrix with different strength was revealed. It was found that phosphate has a significant influence on the type of these species, their number, location in the structure, and strength of binding. Well dispersed Cu2+ complexes with axial symmetry are formed in the semicrystalline part of the starch linked through O−P− bonds in the phosphorylated starches. In the amorphous part of the starch, freely rotating hexaaqua complexes of Cu2+ and complexes coupled antiferromagnetically are formed. The amount of the former increases with content of phosphate indicating enhanced binding of water in the granules. The results complement previous experimental data and molecular models for the starch granule with respect to the location and effects of phosphate and crystalline matter.
ISSN:1525-7797
1526-4602
DOI:10.1021/bm050919g