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Crystalline NADP-Dependent D-Mannitol Dehydrogenase from Gluconobacter suboxydans
O Adachi1, H Toyama1, K Matsushita1
1a Laboratory of Applied Microbiology, Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University.
Bioscience, Biotechnology, and Biochemistry
|July 10, 2016
Summary
Researchers purified and crystallized D-Mannitol dehydrogenase from Gluconobacter suboxydans. This NADP-dependent enzyme is highly specific for D-fructose measurement, offering advantages for enzymatic analysis.
Area of Science:
- Biochemistry
- Enzymology
- Microbial Metabolism
Background:
- D-Mannitol dehydrogenase (EC 1.1.1.138) is crucial for carbohydrate metabolism.
- Previous studies lacked purified and characterized NADP-dependent D-mannitol dehydrogenase from Gluconobacter suboxydans.
Purpose of the Study:
- To purify and crystallize D-Mannitol dehydrogenase from Gluconobacter suboxydans IFO 12528.
- To characterize the enzyme's properties and assess its potential for D-fructose quantification.
Main Methods:
- Enzyme purification using ammonium sulfate fractionation, DEAE-Sephadex A-50 chromatography, and Sephadex G-75 gel filtration.
- Crystallization via ammonium sulfate addition.
- Enzyme characterization through analytical ultracentrifugation, SDS-PAGE, and kinetic studies.
Main Results:
- Successfully purified D-Mannitol dehydrogenase approximately 100-fold, achieving high purity and crystallization.
- Separated the NADP-dependent enzyme from the NAD-dependent form (EC 1.1.1.67).
- Determined the enzyme's molecular mass (50 kDa) and sedimentation constant (3.6 s).
- Demonstrated specific catalysis of D-mannitol oxidation and D-fructose reduction using NADP/NADPH, with NAD/NADH being inert.
- Observed a reaction equilibrium favoring D-fructose reduction, indicating high specificity and stoichiometric NADPH oxidation for D-fructose measurement.
Conclusions:
- The purified and crystallized D-Mannitol dehydrogenase from Gluconobacter suboxydans is a distinct NADP-dependent enzyme.
- Its high specificity and favorable reaction equilibrium make it suitable for direct enzymatic D-fructose measurement.
- This enzyme offers a valuable tool for biochemical analysis and potentially industrial applications involving D-fructose.
