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An improved enzyme assay for molybdenum-reducing activity in bacteria
M Y Shukor1, M F A Rahman, N A Shamaan
1Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. yunus@biotech.upm.edu.my
Applied Biochemistry and Biotechnology
|June 17, 2008
Summary
Researchers identified a superior substrate, 10:4-phosphomolybdate, for molybdenum-reducing enzymes in heterotrophic bacteria. This new substrate significantly enhances enzyme activity, aiding in enzyme purification and understanding molybdenum metabolism.
Area of Science:
- Biochemistry
- Microbiology
Background:
- Molybdenum-reducing activity in heterotrophic bacteria has been known for over a century.
- Bacterial colonies turn blue in the presence of molybdenum, indicating reduction.
- The specific enzyme(s) responsible for this reduction have not been purified.
Purpose of the Study:
- To purify the molybdenum-reducing enzyme from heterotrophic bacteria.
- To develop an improved substrate for assaying molybdenum-reducing enzyme activity.
Main Methods:
- Laboratory preparation of phosphomolybdate substrates.
- Enzyme activity assays using different phosphomolybdate concentrations and electron donors (NADH, NADPH).
- Determination of kinetic parameters (Km and Vmax).
Main Results:
- Laboratory-prepared 10:4-phosphomolybdate demonstrated the highest enzyme activity.
- The apparent Vmax using NADH and 10:4-phosphomolybdate was approximately 13 times higher than with 12-phosphomolybdate.
- Kinetic parameters (Km and Vmax) were determined for 10:4-phosphomolybdate and electron donors NADH and NADPH.
Conclusions:
- 10:4-phosphomolybdate is a significantly better substrate for molybdenum-reducing enzymes than 12-phosphomolybdate.
- This improved substrate facilitates the purification of molybdenum-reducing enzymes.
- The routine preparation of 10:4-phosphomolybdate from common laboratory chemicals (phosphate and molybdate) is feasible.
