Glycoprotein nature of tannase in Aspergillus niger.

1. Tannase (tannin acyl-hydrolase, EC 3.1.1.20) was isolated from the culture medium of Aspergillus niger and purified about 200-fold. On polyacrylamide-gel electrophoresis it gave a single band. 2. The molecular weight of the enzyme was of the order of 55 000 as determined by gel filtration. The enzyme contains 21.5% of carbohydrates (mannose and glucose). 3. Treatment of tannase with alkaline borohydride decreased the content of threonine, serine and mannose, suggesting that the carbohydrate-peptide linkage is of the O-glycoside type, involving mannose linked to threonine and serine.