Cassia grandis Linn. f. seed galactomannan: structural and crystallographical studies.
Cassia grandis is a small or medium sized tree, found in abundance throughout India. The seeds contain about 50% endosperm gum and possess the characteristics of becoming a potential source of seed gum. The purified polysaccharide has been characterized as a pure galactomannan having a mannose-galactose ratio of 3.15; molecular weight (Mw) 80,200; polydispersity (Mw/Mn), 1.35 and intrinsic viscosity [eta], 848 mL/g. Methylation, periodate oxidation, Smith degradation and 13C NMR studies confirm that the polysaccharide has the basic structure of legume galactomannans consisting of a beta-(1-->4)-linked main mannan backbone to which galactose units are attached at O-6. The orthorhombic lattice constants of the hydrated gum are as follows: a=9.00, b=24.81, c=10.30 A. The crystallographic data establish that the probable space group symmetry of the unit cell is P2(1)2(1)2. The results are in contradiction to earlier reports (Indian J. Chem. 16B (1978) 966; J. Indian Chem. Soc. 55 (1978) 1216) in which a non-galactomannan polysaccharide structure has been assigned having a main chain of (1-->4)-linked galactose and mannose units in the molar ratio 6:3, where 50% of the galactose units branched with two galactose and one mannose through 1-->3 linkage.
Joshi
Harsha
H
National Botanical Research Institute, Rana Pratap Marg, Lucknow 226 001, India.
Kapoor
Virendra P
VP
D002240:Carbohydrate Sequence; D002366:Cassia / Q000737:chemistry*; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D018360:Crystallography, X-Ray; D005690:Galactose / Q000032:analysis / Q000031:analogs & derivatives; D008401:Gas Chromatography-Mass Spectrometry; D005947:Glucose / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007194:India; D009682:Magnetic Resonance Spectroscopy; D008351:Mannans / Q000032:analysis / Q000737:chemistry*; D008358:Mannose / Q000032:analysis; D008670:Metals / Q000032:analysis; D008745:Methylation; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010429:Pentoses / Q000032:analysis; D010940:Plant Proteins / Q000032:analysis; D012639:Seeds / Q000737:chemistry*; D014783:Viscosity
D008351:Mannans; D008670:Metals; D010429:Pentoses; D010940:Plant Proteins; C012990:galactomannan; D005947:Glucose; D008358:Mannose; D005690:Galactose