Endoglucanase V and a phosphatase from Trichoderma viride are able to act on modified exopolysaccharide from Lactococcus lactis subsp cremoris B40

EPS B40 from Lactococcus lactis subsp. cremoris consists of a repeating uni t of --> 4)-beta-D-Glcp-(1 --> 4)-[alpha-L-Rhap(1 --> 2)][alpha-D-Galp-1 -P O4-3]-beta-D-Galp-(1 --> 4)-beta-D-Glcp-(1 -->. A phosphatase from Trichode rma viride was able to release phosphate, but only after removal of rhamnos yl and galactosyl residues by mild CF3CO2H treatment. Purified endoV from T . virine was able to act on the backbone of the polymer, but only if rhamno syl substituents and phosphate had been removed. After complete removal of phosphate and partial removal of rhamnosyl residues by HF treatment, incuba tion with endoV resulted in a homologous series of oligomers. Purification of these oligomers and subsequent characterisation by NMR demonstrated that endoV was able to cleave the beta-(1 --> 4) linkage between two glucopyran osyl residues when the galactopyranosyl residue towards the nonreducing end is unsubstituted. The mode of action of endoV on HF-treated EPS B40 is dis cussed on the basis of the subsite model described for endoV [J.-P. Vincken , G. Beldman, A.G.J. Voragen, Carbohydr. Res., 298 (1997) 299-310]. (C) 199 9 Elsevier Science Ltd. All rights reserved.