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A spectrophotometric assay for alpha-mannosidase activity
C H Scaman1, F Lipari, A Herscovics
1Department of Chemistry, University of Alberta, Edmonton, Canada.
Glycobiology
|April 1, 1996
Summary
A new spectrophotometric assay accurately measures alpha-mannosidase activity using natural or synthetic substrates. This method quantifies released mannose, offering a versatile alternative to traditional assays for enzyme kinetics and substrate evaluation.
Area of Science:
- Biochemistry
- Enzymology
Background:
- Alpha-mannosidase is a key enzyme involved in glycoprotein metabolism.
- Accurate measurement of alpha-mannosidase activity is crucial for understanding various biological processes and diseases.
Purpose of the Study:
- To develop a simple, versatile spectrophotometric assay for alpha-mannosidase activity.
- To evaluate the assay's performance using recombinant enzyme and compare it with traditional methods.
- To assess alternative oligosaccharides as potential substrates for alpha-mannosidase.
Main Methods:
- Development of a spectrophotometric assay quantifying reducing mannose released from substrates.
- Enzyme kinetic analysis using recombinant Saccharomyces cerevisiae alpha 1,2-mannosidase and Man9GlcNAc.
- Evaluation of Man5-O(CH2)8-COOCH3 as a synthetic substrate.
Main Results:
- The developed assay provides reliable kinetic parameters (Km = 0.3 mM, Vmax = 15 mU/µg) comparable to radiochemical methods.
- Man5-O(CH2)8-COOCH3 demonstrates potential as an alternative synthetic substrate, retaining enzyme specificity.
- Kinetic data indicate the lower 1,3-linked arm of Man9GlcNAc is more critical for substrate recognition.
Conclusions:
- A robust and adaptable spectrophotometric assay for alpha-mannosidase activity has been established.
- The assay facilitates efficient enzyme characterization and substrate screening.
- Findings provide insights into the substrate specificity and kinetic properties of alpha-mannosidase.