Pineapple α- and β-d-Mannopyranosidases and Their Action on Core Glycopeptides

Y-and fi-D-Mannopyranosidases from crude pineapple bromelain were isolated and purified.The specificities of these enzymes were tested with synthetic and natural mannosides.The b-D-mannosidase completely released the terminal D-mannose from Man -+ GlcNAc --f GlcNAc + Asn obtained from ovalbumin and Aspergitlus oryzae ar-amylase.The ar-D-mannosidase was inactive toward the core glycopeptides.Physical data also support the presence of P-D- mannosyl linkage in the core glycopeptides.It has been previously reported (1) that a Man + GlcNAc -+ GlcNAc + Asn sequence is present in a number of glycoproteins from a variety of sources.The terminal mannosyl residue in this sequence is resistant to action of the or-n-mannosidases from sweet almond emulsin (2) and jack bean meal (3).We are now able to demonstrate that its terminal n-mannosyl linkage resistant to a-n-mannosidases can be cleaved by a pineapple @-n-mannosidase.Physical data also support that this linkage is of fl configuration.EXPERIMENTAL PROCEDURE Materials-Crude pineapple bromelain was donated by Dole Co., Honolulu, Hawaii.Various glycosidase activities present in such a preparation are shown in Table I.Asparagine oligosaccharides from ovalbumin (4) and Aspergillus oryzae cY-amylase (5) were prepared as described before.2-Acetamido-l-N-(4-L-aspartyl)-2-deoxy-/?-D-glucopyranosylamine (I) was a gift from Dr. G. Johnson.