Isolation of Actin and Myosin Filaments
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Isolation of Actin and Myosin Filaments
LEVEL III
Materials
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Relaxing Solution
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0.1 M KCl
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0.001 M MgCl
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5 mM ATP
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0.016 M NaH PO
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Na HPO
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Adjust pH to 7.3
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0.1 M KCl
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0.05 M Sodium phosphate buffer, pH 7.0
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0.001 M EDTA (Ethylene diamine tetra acetic acid)
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Blender
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Preparative centrifuge
- Materials for TEM fixation, embedding and observation
Procedure 7
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Obtain fresh chicken gizzards 8 and dissect the lateral muscles free from all attachments. Place the muscles on crushed ice and then grind them in a standard worm- drive meat grinder. Small samples can be pushed through a hand press, if desired.
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Weigh the tissue and add an equal volume of cold 0.05 M Sodium phosphate buffer, pH 7.0 with 0.001 M EDTA. Blend this mix in a standard blender at low speed and pour the slurry into a large beaker.
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Upon settling, the muscle fragments will settle on top of the underlying connective tissue. Separate the two by decanting, and concentrate by low speed centrifugation.
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Suspend aliquots of blended muscle in two volumes of relaxing solution and homogenize in a blender at high speed for 30 seconds.
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Centrifuge the homogenate at 500 xg to remove membraneous organelles and whole cells. The myofilaments are preferentially localized in the middle, clear solution of the centrifuge tube.
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Collect the middle layer and recentrifuge at 40,000 xg to pellet the myofilaments. Wash and gently resuspend. This will rid the preparation of soluble proteins.
- Prepare a small sample of the middle layer from Step 5 for EM observation, following the procedure outlined above for tubulin ( Exercise 9.7 ).