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Isolation and properties of mesosomal membrane fractions from Micrococcus lysodeikticus
Abstract:
1. A method is described for the isolation of pure mesosomal membrane fractions from Micrococcus lysodeikticus. 2. Plasmolysis of cells, before wall digestion, was necessary for effective mesosome release. 3. The effect of mild shearing forces, temperature and time upon the release of mesosomal membrane from protoplasts was investigated. 4. The optimum yield of mesosomal membranes from stable protoplasts was achieved at 10mm-Mg(2+). 5. Mesosomal membrane vesicle fractions prepared at differing Mg(2+) concentrations above 10mm were similar in chemical composition. 6. Comparison of the properties of peripheral and mesosomal membrane fractions revealed major differences in the distribution of protein components, membrane phosphorus, mannose and dehydrogenase activities between the two fractions. 7. Only cytochrome b(556) was detected in mesosomal membranes, whereas peripheral membranes contained a full complement of cytochromes. 8. Preliminary investigations suggested the localization of an autolytic enzyme(s) in the mesosomal vesicles. 9. The anatomy of mesosomal and peripheral membrane have been compared by the negative-staining and freeze-fracture technique. 10. The results are discussed in relation to a plausible role for the mesosome.
Insights
Researchers developed a method to isolate pure mesosomal membranes from Micrococcus lysodeikticus. This involved plasmolysis and optimizing magnesium ion concentration for effective mesosome release and characterization.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Mesosomes are intracellular membrane structures in bacteria.
- Their function and isolation have been challenging.
- Understanding mesosome composition is key to elucidating their role.
Purpose of the Study:
- To develop and optimize a method for isolating pure mesosomal membrane fractions.
- To characterize the biochemical and structural properties of mesosomal membranes.
- To compare mesosomal membranes with peripheral membranes.
Main Methods:
- Cell plasmolysis prior to wall digestion for mesosome release.
- Optimization of Mg(2+) concentration, shearing forces, temperature, and time.
- Chemical composition analysis (protein, phosphorus, mannose, enzyme activities).
- Cytochrome content analysis.
- Structural analysis using negative-staining and freeze-fracture techniques.
Main Results:
- Plasmolysis is crucial for effective mesosome release.
- Optimal mesosome yield at 10mm Mg(2+).
- Mesosomal and peripheral membranes differ significantly in protein distribution, phosphorus, mannose, and dehydrogenase activities.
- Mesosomal membranes contain only cytochrome b(556), unlike peripheral membranes.
- Autolytic enzyme(s) may be localized in mesosomal vesicles.
Conclusions:
- A reliable method for isolating pure mesosomal membranes from Micrococcus lysodeikticus was established.
- Significant biochemical and structural differences exist between mesosomal and peripheral membranes.
- These findings provide insights into the potential functions of bacterial mesosomes.