A novel α1,2-L-fucosidase acting on xyloglucan oligosaccharides is associated with endo-β-mannosidase

Endo-p-mannosidase, which hydrolyses the Man beta 1-4GlcNAc linkage of N-glycans in an endo-manner, was discovered in plants. During the course of the purification of the enzyme from lily flowers, we found a higher molecular mass form of the enzyme (designated as EBM II). EBM II was purified by column chromatography to homogeneity and its molecular composition revealed EBM H to be comprised of endo-p-mannosidase and an associated protein. The cDNA of this associated protein encodes a protein with slight homology to the fucosidase domain of bifidus A&A. EBM II has alpha 1,2-L-fucosidase activity and acts on a fucosylated xyloglucan nonasaccharide. The amino acid sequence of this associated protein has no similarity to known plant alpha-L-fucosidases. These results show that EBM II is a novel alpha 1,2-L,-fucosidase and a protein complex containing endo-beta-mannosidase.