Studies on L-rhamnosidase. Part IV. Synthesis of certain disaccharides containing a .ALPHA.- or .BETA.-L-rhamnopyranosidic group and the substrate specificity of .ALPHA.-L-rhamnosidase from Aspergillus niger.

To investigate the substrate specificity of α-L-rhamnosidase from Aspergillus niger, the following seven substrates were synthesized: methyl 3-O-α-L-rhamnopyranosyl-α-D-mannopyranoside (1), methyl 3-O-α-L-rhamnopyranosyl-α-D-xylopyranoside (2), methyl 3-O-α-L-rhamnopyranosyl-α-L-rhamnopyranoside (3), methyl 4-O-α-L-rhamnopyranosyl-α-D-galactopyranoside (4), methyl 4-O-α-L-rhamnopyranosyl-α-D-mannopyranoside (5), methyl 4-O-α-L-rhamnopyranosyl-α-D-xylopyranoside (6), and 6-O-β-L-rhamnopyranosyl-D-mannopyranose (7). Compounds 1∼6 were well-hydrolyzed by the crude enzyme, but 7 was unaffected.