| Autor: |
Eneyskaya, Elena V., Kulminskaya, Anna A., Savel'ev, Andrew N., Shabalin, Konstantin A., Golubev, Alexander M., Neustroev, Kirill N. |
| Zdroj: |
Biochemical and Biophysical Research Communications; April 1998, Vol. 245 Issue: 1 p43-49, 7p |
| Abstrakt: |
The 160 kDa α-mannosidase (E.C. 3.2.1.24) isolated from culture filtrate ofTrichoderma reeseihas wide aglycon specificity but cleaves the α1 → 2 and α1 → 3 mannosidic bonds with higher rate than α1 → 6 bond and slowly hydrolyses yeast mannan and 1,6-α-mannan. The specific activity of the enzyme and rate constant in the reaction with p-nitrophenyl-α-D-mannopyranoside were 0.15 U/mg and 1.62 × 10−4μM/min/μg, respectively, at optimal pH 6.5. We have found thatin vitroenzyme is able to cleave off 30% of total α-mannopyranosyl residues fromN- andO-linked glycans of secreted glycoproteins. The activity of the α-mannosidase toward glycoproteinsin vivowas studied comparing the structures ofO- andN-linked glycans of glycoproteins isolated from the cultures growing with and without 1-deoxymannojirimycin, an inhibitor of α-mannosidases. Difference in structures of these glycans may be explained by postsecretory deglycosylation catalysed by the α-mannosidase. |
| Databáze: |
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