1. Purification and properties of beta-mannosidase from malted barley
- Author
-
Clifford W. Houston, Steve B. Latimer, and Earl D. Mitchell
- Subjects
Glycoside Hydrolases ,Cleavage (embryo) ,Binding, Competitive ,Chromatography, DEAE-Cellulose ,Nitrophenols ,Drug Stability ,Polyacrylamide gel electrophoresis ,Volume concentration ,β mannosidase ,chemistry.chemical_classification ,Chromatography ,Chemistry ,Temperature ,Substrate (chemistry) ,Hexosamines ,Hordeum ,General Medicine ,Hydrogen-Ion Concentration ,Plants ,Chromatography, Ion Exchange ,Enzyme Activation ,Molecular Weight ,Electrophoresis ,Kinetics ,Enzyme ,Chromatography, Gel ,Electrophoresis, Polyacrylamide Gel ,Competitive inhibitor ,Mannose - Abstract
β-Mannosidase (β-mannoside mannohydrolase, EC 3.2.1.25) was extracted and purified about 100-fold from malted barley. The purified preparation was free of α-mannosidase, β-N-acetylhexosaminidase, α-galactosidase and β-glucosidase. The purified enzyme was active between pH 3 and 6 and exhibited a Km value of 3.2·10−4 M using the p-nitrophenyl-β-d-mannopyranoside as the substrate. 2-Amino-2-deoxy-d-mannose is a competitive inhibitor (K1 = 1.18·10−4 M), p-Nitrophenyl-α-d-mannopyranoside activated the enzyme at low concentration but competitively inhibits at higher concentrations. β-Mannosidase had maximum activity at 55 °C but this dropped significantly at 70 °C. Specific cleavage of β-mannoside linkages by the purified β-mannosidase was demonstrated using a β-(1–4)mannosylmannose as substrate. The enzyme showed the molecular weight is about 88 000 as determined by acrylamide gel electrophoresis.
- Published
- 1974