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Metalloenzyme inhibitor from kidney beans: partial purification and characterization.
Y Hojima1, H Moriya, C Moriwaki
1Faculty of Pharmaceutical Sciences, Science University of Tokyo, Shinjuku-ku, Tokyo 162, Japan.
Plant Physiology
|March 1, 1979
Summary
A red kidney bean extract contains a small molecule inhibitor that chelates zinc (Zn2+). This potent inhibitor effectively blocks metalloenzymes like carboxypeptidase A and B, and alkaline phosphatase.
Area of Science:
- Biochemistry
- Enzymology
- Plant Biochemistry
Background:
- Metalloenzymes are crucial biological catalysts that often require metal ions, such as zinc (Zn2+), for their activity.
- Inhibitors of metalloenzymes have therapeutic potential and are valuable tools for biochemical research.
- Natural sources are often explored for novel enzyme inhibitors.
Purpose of the Study:
- To purify and characterize an inhibitor of metalloenzymes from red kidney beans (Phaseolus vulgaris).
- To elucidate the mechanism of inhibition and identify the target enzymes.
- To assess the inhibitor's properties, including molecular weight, metal chelating ability, and effect on enzyme activity.
Main Methods:
- Purification of inhibitory substance from red kidney bean extracts.
- Enzyme inhibition assays using carboxypeptidase A, carboxypeptidase B, alkaline phosphatase, and phosphoglucomutase.
- Determination of inhibitor's molecular weight, isoelectric point, and metal chelating properties.
- Investigation of inhibitor's interaction with various metal ions (Zn2+, Ni2+, Co2+, Cu2+).
Main Results:
- A low molecular weight inhibitor was purified from red kidney beans.
- The inhibitor demonstrated potent inhibition of carboxypeptidase A (1 mg inhibited 23 mg), carboxypeptidase B, and alkaline phosphatase.
- The inhibitor acts as a zinc (Zn2+) chelator, removing the metal ion essential for the activity of these enzymes.
- Inhibitor activity was abolished upon preincubation with Zn2+, Ni2+, Co2+, or Cu2+.
- The inhibitor could activate phosphoglucomutase previously inactivated by Zn2+.
Conclusions:
- Red kidney beans contain a potent zinc-chelating inhibitor of metalloenzymes.
- The inhibitor's mechanism involves the complexation and removal of zinc from the active site of enzymes like carboxypeptidases and alkaline phosphatase.
- This plant-derived inhibitor shows promise for biochemical research and potential therapeutic applications targeting zinc-dependent enzymes.