CHARCTERISATION OF THE OLIGOSACCHARIDES PRODUCED ON HYDROLYSIS OF GALACTOMANNAN WITH β-D-MANNANASE

Article abstract of DOI:10.1016/0008-6215(83)88038-0

Treatment of hot-water-soluble carob galactomannan with β-D-mannanases from A. niger or lucerne seed affords an array of D-galactose-containing β-D-mannosaccharides as well as β-D-manno-biose, -triose, and tetraose (lucerne-seed enzyme only).The D-galactose-containing β-D-mannosaccharides of d.p. 3-9 produced by A. niger β-D-mannanase have been characterised, using enzymic, n.m.r., and chemical techniques, as 6¹-α-D-galactosyl-β-D-mannobiose, 6¹-α-D-galactosyl-β-D-mannotriose, 6³,6⁴-di-α-D-galactosyl-β-D-mannopentaose (the only heptasaccharide), and 6³,6⁴-di-α-D-galactosyl-β-D-mannohexaose, 6⁴,6⁵-di-α-D-galactosyl-β-D-mannohexaose, and 6¹,6³,6⁴-tri-α-D-galactosyl-β-D-mannopentaose (the only octasaccharides).Four nonasaccharides have also been characterised.Penta- and hexa-saccharides were absent.Lucerne-seed β-D-mannanase produced the same branched tri-, tetra- and hepta-saccharides, and also penta- and hexa-saccharides that were characterised as 6¹-α-D-galactosyl-β-D-mannotetraose, 6³-α-D-galactosyl-β-D-mannotetraose, 6¹,6³-di-α-D-galactosyl-β-D-mannotetraose, 6³-α-D-galactosyl-β-D-mannopentaose, and 6⁴-α-D-galactosyl-β-D-mannopentaose.None of the oligosaccharides contained a D-galactose stub on the terminal D-mannosyl group nor were they substituted on the second D-mannosyl residue from the reducing terminal.