Isolation, fine structure and morphology studies of galactomannan from endosperm of Gleditsia japonica var. delavayi.

The water-soluble polysaccharides extracted from endosperm of Gleditsia japonica var. delavayi seeds (EGSP) were identified as galactomannan having the M/G ratio of 2.54-2.66 and a weight average molecular weight (Mw) of 1913 kDa. The molecular structure of EGSP was determined by periodate oxidation, Smith degradation, methylation, FTIR and NMR spectroscopy. The main chain is composed of β-1,4-d-mannopyranose and the branches composed of single α-1-d-galactopyranose. We had also established a model to speculate the fine structure of galactomannan molecules and given preliminary results. The I2-KI test indicated that there were many branches on the EGSP backbone and no starch in EGSP. The CD spectra and Congo red test showed EGSP was random coil conformations in solution and could form a small quantity of helical conformation under alkaline conditions. The microstructure of morphology was observed by OM, SEM and AFM. The results showed that the fibers composed of multiple microfibers formed a network construction by entangling with each other.