[Determination of the primary and fine structures of galactomannan from seeds of Gleditsia triacanthos f. intermis L].

Abstract

This was the first study to isolate galactomannan, a 660-kDa polysaccharide, from the seeds of Gleditsia triacanthos f. inermis L. (yield 15.4%). Its aqueous solutions were optically active ([alpha] D = +31.0 degrees) and highly viscous ([eta] = 578 ml/g). The analysis of this heteropolysaccharide using chemical, enzymatic, and chromatographic procedures, as well as IR- and 13C-NMR spectroscopy, showed that is consists of D-mannopyranose and D-galactopyranose residues (molar ratio 2.42:1). Its main chain is comprised of 1,4-beta-D-mannopyranose residues, 41% of which is substituted at C-6 with single residues of alpha-D-galactopyranose. The probability of occurrence of differently substituted mannobiose units in the chain, determined experimentally, was 0.16 for the unit Man-Man, 0.50 for the units Gal(Man-Man) and (Man-Man)Gal, and 0.34 for the dissubstitued unit Gal(Man-Man)Gal.