title: The distribution of covalently bound phosphate in the starch granule in relation to starch crystallinity.
abstract: Five selected starches with a 60-fold span in their content of monoesterified starch phosphate were investigated with respect to distribution of glucose 6-phosphate and glucose 3-phosphate residues, amylopectin chain length distributions and gelatinisation properties. The distribution of starch phosphate in the starch granules was determined by preparation of Nägeli dextrins followed by quantitative 31P-nuclear magnetic resonance spectroscopy. Total starch phosphate content was positively correlated to the unit chain lengths of the amylopectin as well as to the chain lengths of the corresponding Nägeli dextrins. The major part (68-92%) of the total starch phosphate content was partitioned to the hydrolysed (amorphous) parts. Starch-bound glucose 6-phosphate per milligram of starch was 2-fold enriched in the amorphous parts, whereas phosphate groups bound at the 3-position were more evenly distributed. The gelatinisation temperatures of the native starches as determined by differential scanning calorimetry were positively correlated (R(2)=0.75) to starch phosphate content, while crystallinity (gelatinisation enthalpy) and crystal heterogeneity (endotherm peak width) showed no correlations to starch phosphate content. The relations between starch molecular structure, architecture and functional properties are discussed.
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant Biology, The Royal Veterinary and Agricultural University, 40 Thorvaldsensvej, 1871 Fredriksberg C, Copenhagen, Denmark. abl@kvl.dk
authors.forename: A
authors.initials: A
authors.lastname: Blennow
authors.forename: A M
authors.initials: AM
authors.lastname: Bay-Smidt
authors.forename: C E
authors.initials: CE
authors.lastname: Olsen
authors.forename: B L
authors.initials: BL
authors.lastname: Møller
mesh_terms: D000687:Amylopectin / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002851:Chromatography, High Pressure Liquid; D003912:Dextrins / Q000737:chemistry; D005780:Gelatin / Q000737:chemistry; D005947:Glucose / Q000031:analogs & derivatives / Q000737:chemistry; D019298:Glucose-6-Phosphate / Q000737:chemistry; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D010710:Phosphates / Q000737:chemistry*; D010766:Phosphorylation; D011198:Solanum tuberosum / Q000737:chemistry; D013213:Starch / Q000737:chemistry*; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D003912:Dextrins; D010710:Phosphates; D019298:Glucose-6-Phosphate; D005780:Gelatin; D013213:Starch; D000687:Amylopectin; D005947:Glucose