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Membrane-bound and soluble extracellular alpha-amylase from Bacillus subtilis
The Journal of Biological Chemistry
|September 10, 1979
Summary
Bacillus subtilis alpha-amylase exists in both extracellular and membrane-bound forms. Membrane-bound alpha-amylase, containing phospholipids, is latent and released by an endogenous enzyme.
Area of Science:
- Biochemistry
- Microbiology
- Enzymology
Background:
- Extracellular alpha-amylase from Bacillus subtilis was purified.
- A membrane-derived alpha-amylase was also isolated and purified.
Purpose of the Study:
- To characterize the relationship between extracellular and membrane-bound alpha-amylase in Bacillus subtilis.
- To investigate the properties and release mechanism of membrane-bound alpha-amylase.
Main Methods:
- Purification of extracellular and membrane-bound alpha-amylase.
- Sodium dodecyl sulfate-gel electrophoresis and radioimmunoassay.
- Phospholipid extraction and analysis.
- Enzymatic release studies under varying pH and with inhibitors/stimulators.
Main Results:
- Extracellular and membrane-bound alpha-amylase are indistinguishable by SDS-PAGE and RIA.
- Membrane-bound alpha-amylase contains phosphatidylethanolamine and is latent.
- Release of membrane-bound enzyme is pH-dependent, inhibited by chelators/DFP, and stimulated by Ca2+/Mg2+.
- The level of membrane-bound alpha-amylase correlates with secretion levels.
Conclusions:
- Bacillus subtilis alpha-amylase exists in both soluble and membrane-associated forms.
- Membrane-bound alpha-amylase is a phospholipid-containing precursor or related form, released by a specific enzymatic process.
- The regulation of membrane-bound alpha-amylase is linked to the overall secretion pathway.
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