ENZYMIC DEGRADATION OF YEAST CELL-WALL MANNANS AND GALACTOMANNANS TO POLYMERIC FRAGMENTS CONTAINING ALPHA(1-]6)-LINKED D-MANNOPYRANOSE RESIDUES

The cell-wall D-mannans of Candida parapsilosis, Endomycopsis fibuliger, Saccharomyces rouxii, Torulopsis apicola (Hajsig strain), and Torulopsis bombi were degraded with an exo α-D-mannosidase from Arthrobacter GJM-1 to their α-(1→6)-linked D-mannopyranose main-chains, as demonstrated by p.m.r. spectroscopy. D-galacto-D-mannans from Candida lipolytica, Torulopsis gropengiesseri, Torulopsis lactis-condensi, Torulopsis magnoliae, and Trichosporon fermentans could be degraded to polysaccharides containing mainly 6-O-linked α-D-mannopyranosyl residues following preferential removal of their enzyme-resistant, D-galactopyranosyl non-reducing end-units with acid. The D-mannans of Saccharomyces lodderi, Citeromyces matritensis, and Pichia pastoris could also be enzymically degraded to polysaccharides containing predominantly α-(1→6)-linked D-mannopyranosyl residues after hydrolysis of most of the β-D-linked residues in their side chains with acid. The exo α-D-mannosidase, as would be expected, produced β-D-mannose on splitting of an α-(1→2)-linked D-mannopyranose tetramer. It is, however, very selective in its action since it did not cleave α-D-Manp-(1→2)-β-D-Manp-(1→2)-β-D-Manp-(1→2)-β-D-Manp-(1→2)-D-Man. Apparently a D-mannopyranose non-reducing end-unit and two consecutive α-D-mannopyranose residues are required by the enzyme for cleavage of a substrate to take place. © 1969.