Action de l'α-galactosidase du café sur quelques galactomannanes

Abstract

Coffee-bean α-galactosidase (3.2.1.22) splits, at similar initial rates, α- D-galactosyl units from various galactomannans isolated from Trifolium repens, Genista scoparia, Gleditschia ferox, Gleditschia triacanthos, and Ceratonia siliqua. Except for white-clover, genista, and carob-tree galactomannans, α-galactosidase treatment resulted in insoluble mannan-like polysaccharides. A water-insoluble fraction containing 24 residues of mannose for each residue of galactose was obtained from the galactomannan of Gleditschia ferox. It contains chains having a β- D-(1 → 4)-mannopyranosyl repeating unit. These chains have probably a few side-branches. The few remaining D-galactose residues are linked (1 → 6) as side-branches to the D-mannose chains.