Isolation of cardiac myofibrils and myosin light chains with in vivo levels of light chain phosphorylation |
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Authors: | Michael J Holroyde David AP Small Elizabeth Howe RJohn Solaro |
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Institution: | Department of Physiology and Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, U.S.A. |
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Abstract: | Conditions are described for the preparation of functional myofibrils and myosin light chains from freeze-clamped beating hearts with the state of light chain phosphorylation chemically ‘frozen’ during the extraction procedure. Myofibrils were shown to be functionally intact by measurement of Ca2+ binding and ATPase activity. Highly purified cardiac myosin light chains could be routinely isolated from myofibrillar preparations using ethanol fractionation together with ion-exchange chromotography. Analysis of light chains for covalent phosphate indicated that basal levels of phosphorylation of the 18?20 000 dalton light chain of myosin in rabbit hearts beating in situ or in a perfusion apparatus were 0.3–0.4 mol/mol. Covalent phosphate content of the light chain fraction did not change during perfusion of hearts with 10 μM epinephrine. |
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Keywords: | Phosphorylation Myosin Catecholamine Light chain (Heart myofibril) P-light chain the 18?20 000 dalton light chain of myosin LC light chain |
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