%0 Journal Article %1 Hjerde1998 %A Hjerde, T. %A Stokke, B. T. %A Smidsrod, O. %A Christensen, B. E. %C THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND %D 1998 %I ELSEVIER SCI LTD %J Carbohydr. Polym. %K ; ;; [ISI:] acid-hydrolysis; aqueous-solution; conformational degradation; depolymerization; ferrous free-radical ions microscopy; polysaccharide; schizophyllan; scleroglucan; transitions; viscosity xanthan; %N 1 %P 41 -- 48 %T Free-radical degradation of triple-stranded scleroglucan by hydrogen peroxide and ferrous ions %V 37 %X The triple-stranded polysaccharide scleroglucan was subjected to free-radical depolymerisation with Fenton's reagent (H2O2/Fe2+), and partially degraded samples in the molecular weight (M-w) range from 8 200 000 to 5200 were studied. Analyses of the chemical composition of partially degraded samples by C-13 nuclear magnetic resonance spectroscopy and by determination of reducing end-groups suggested that the degradation was random. The decrease in M-w followed the kinetics expected for a multiple-stranded polymer. Following an apparently initial stable regime, degradation occurred with an exponential decrease (exponent (nu) similar to 3.6) in M-w. Partially degraded samples displayed bimodal molecular weight distributions. This was attributed to the release of single-stranded oligomers having a degree of polymerisation (DP) too low to remain incorporated in the tripler structure (DP < DP,; the critical lower DP far tripler formation). The weight-average molecular weight of the low-M-w fraction was estimated to about 36 000 (DP(w)similar to 56 tetrasaccharide units). Following a heat treatment at 100 degrees C (15 min) of the partially degraded samples, a reduction in M-w by a factor of 2 to 2.5 was observed. This was attributed to the formation of more perfectly matched triple-stranded molecules, without aggregation or ring formation, as shown by electron microscopy. (C) 1998 Elsevier Science Ltd. All rights reserved.

@article{Hjerde1998, __markedentry = {[phpts:6]}, abstract = {The triple-stranded polysaccharide scleroglucan was subjected to free-radical depolymerisation with Fenton's reagent (H2O2/Fe2+), and partially degraded samples in the molecular weight (M-w) range from 8 200 000 to 5200 were studied. Analyses of the chemical composition of partially degraded samples by C-13 nuclear magnetic resonance spectroscopy and by determination of reducing end-groups suggested that the degradation was random. The decrease in M-w followed the kinetics expected for a multiple-stranded polymer. Following an apparently initial stable regime, degradation occurred with an exponential decrease (exponent (nu) similar to 3.6) in M-w. Partially degraded samples displayed bimodal molecular weight distributions. This was attributed to the release of single-stranded oligomers having a degree of polymerisation (DP) too low to remain incorporated in the tripler structure (DP < DP,; the critical lower DP far tripler formation). The weight-average molecular weight of the low-M-w fraction was estimated to about 36 000 (DP(w)similar to 56 tetrasaccharide units). Following a heat treatment at 100 degrees C (15 min) of the partially degraded samples, a reduction in M-w by a factor of 2 to 2.5 was observed. This was attributed to the formation of more perfectly matched triple-stranded molecules, without aggregation or ring formation, as shown by electron microscopy. (C) 1998 Elsevier Science Ltd. All rights reserved.}, added-at = {2011-11-04T13:47:04.000+0100}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, author = {Hjerde, T. and Stokke, B. T. and Smidsrod, O. and Christensen, B. E.}, authoraddress = {Norwegian Univ Sci & Technol, Dept Biotechnol, NTNU, N-7034 Trondheim, Norway. ; Norwegian Univ Sci & Technol, Dept Phys, NTNU, N-7034 Trondheim, Norway.}, biburl = {https://www.bibsonomy.org/bibtex/286221076300ad270c9d8838c76dcc1bb/pawelsikorski}, citedref = {BOHN JA, 1995, CARBOHYD POLYM, V28, P3 ; CHRISTENSEN BE, 1991, CARBOHYD RES, V214, P55 ; CHRISTENSEN BE, 1993, MACROMOLECULES, V26, P6111 ; CHRISTENSEN BE, 1996, CARBOHYD RES, V280, P85 ; CHRISTENSEN BE, 1996, MACROMOLECULES, V29, P2939 ; DAVISON P, 1982, SOC PET ENG J JUN, P353 ; DUBOIS M, 1956, ANAL CHEM, V28, P350 ; HERP A, 1967, CARBOHYD RES, V4, P63 ; HJERDE T, 1994, CARBOHYD POLYM, V24, P265 ; HJERDE T, 1996, CARBOHYD RES, V288, P175 ; HJERDE T, 1998, MACROMOLECULES, V31, P1842 ; HODGE JE, 1962, METHODS CARBOHYDRATE, V1, P380 ; KITAMURA S, 1989, BIOPOLYMERS, V28, P639 ; KITAMURA S, 1996, BIOPOLYMERS, V39, P407 ; KNUTSEN SH, 1993, HYDROBIOLOGIA, V260, P667 ; MCINTIRE TM, 1995, MACROMOLECULES, V28, P6375 ; NORISUYE T, 1980, J POLYM SCI POL PHYS, V18, P547 ; RINAUDO M, 1980, INT J BIOL MACROMOL, V2, P45 ; RINAUDO M, 1982, CARBOHYD POLYM, V2, P135 ; SHARPLES A, 1957, T FARADAY SOC, V53, P1003 ; SMIDSROD O, 1965, ACTA CHEM SCAND, V19, P143 ; STOKKE BT, 1992, MACROMOLECULES, V25, P2209 ; STOKKE BT, 1993, BIOPOLYMERS, V33, P193 ; STOKKE BT, 1994, MICRON, V25, P469 ; THOMAS CA, 1956, J AM CHEM SOC, V78, P1861 ; TYLER JM, 1980, J ULTRASTRUCT RES, V71, P95 ; UCHIYAMA H, 1990, J BIOL CHEM, V265, P7753 ; WELLINGTON SL, 1983, SOC PET ENG J DEC, P901 ; YANAKI T, 1983, BIOPHYS CHEM, V17, P337}, interhash = {6adda4ae75b37d9d6fdce80b6b8775ab}, intrahash = {86221076300ad270c9d8838c76dcc1bb}, isifile-dt = {Article}, isifile-ga = {136AK}, isifile-j9 = {CARBOHYD POLYM}, isifile-nr = {29}, isifile-pi = {OXFORD}, isifile-rp = {Christensen, BE, Norwegian Univ Sci & Technol, Dept Biotechnol, NTNU, ; N-7034 Trondheim, Norway.}, isifile-sc = {Chemistry, Applied; Chemistry, Organic; Polymer Science}, isifile-tc = {6}, issn = {0144-8617}, journal = {Carbohydr. Polym.}, keywords = {; ;; [ISI:] acid-hydrolysis; aqueous-solution; conformational degradation; depolymerization; ferrous free-radical ions microscopy; polysaccharide; schizophyllan; scleroglucan; transitions; viscosity xanthan;}, language = {English}, month = SEP, number = 1, owner = {phpts}, pages = {41 -- 48}, publisher = {ELSEVIER SCI LTD}, size = {8 p.}, sourceid = {ISI:000076835300006}, timestamp = {2011-11-04T13:47:12.000+0100}, title = {Free-radical degradation of triple-stranded scleroglucan by hydrogen peroxide and ferrous ions}, volume = 37, year = 1998 }