Selective removal of α-d-galactose side chains from Rhizobium capsular polysaccharide by guar α-d-galactosidase: effect on conformational stability and gelation
✍ Scribed by Michael J. Gidley; Gillian Eggleston; Edwin R. Morris
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 834 KB
- Volume
- 231
- Category
- Article
- ISSN
- 0008-6215
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✦ Synopsis
a-o-Galactosidase, isolated from germinating seeds of guar, removed up to 48% of the (1 --) 2)-linked cu-o-galactose side chains of Rhizobium capsular polysaccharide (CPS), with no loss of the disaccharide side chains cl+ 6Hinked to the same backbone residues in the hexasaccharide repeating units. Results from differential scanning calorimetry (DSC) and measurements of gel rigidity (G') indicate that removal of cY-o-galactose side chains facilitates adoption of the "pseudo double-helical" structure proposed from X-ray fibre diffraction analysis (increase in T,,, and reduction in DSC peak width for conformational ordering on cooling), but progresskely eliminates the helix-helix aggregation necessary for gel formation (reduction in thermal hysteresis and in G').