| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1992: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1991: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
1) The molecular basis for the rheological characteristics of xanthan gum, a polysaccharide produced by the plant pathogen Xanthomonas campestris, was studied using a rheogoniometer and polarimeter. Possible mode of intramolecular associations in xanthan molecules were proposed. Possible binding sites for D-mannose-specific interaction between xanthan and galactomannan (locust-bean gum) have also been proposed. The rheological characteristics of a mixture of xanthan (native, deacetylated, depyruvated, and deacylated) with tara-bean gum, and with konjac glucomannan agreed with those in the mixture with locust-bean gum, and supported the possible association sites between xanthan and locust-bean gum in aqueous solution. The interaction between the extracellular bacterial polysaccharide xanthan and typical galactomannan and glucomannan components of the plant cell wall may play a part in the host-pathogen relationship, and may provide the existence of D-mannose-specific binding sites used
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for cell recognition by the pathogen.
2) Molecular origin for thermal stability of welan and rhamsan, the structure of which are similar to that of gellan gum which formed a stiff, brittle gel in aqueous solution, might be attributed to the intramolecular associations. Possible mode of intramolecular association between the OH-4 of the D-glucosyl residue and the adjacent hemiacetal oxygen atom of the L-rhamnosyl residue, and between the methyl group of the L-rhamnosyl residue and the adjacent hemiacetal oxygen atom of the D-glucoslyl residue were proposed.
3) The molecular origin for gel-formation of alginate in the presence of Ca^<2+> might be attributed to the intramolecular hydrogen bonding and Ca-bridge, and to the intermolecular Ca-bridges in aqueous solution. Possible mode of intramolecular hydrogen bonding and Ca-bridge, and intermolecular Ca-bridges were proposed.
4) The molecular origin for gel-formation of curdlan might be attributed to the intra- and intermolecular hydrogen bonding. Possible mode of intra- and inter-molecular associations within and between curdlan molecules were proposed. An hydrophobic interaction might take place at high temperature, the mode of which was also proposed. Less
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