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Myosin adenosinetriphosphatase activity and light chain subunit composition of human right and left ventricle
Abstract:
Myosin was isolated from the free right and left ventricular wall of normal adult human myocardium and purified until actin contamination was considered negligible as judged by sodium dodecyl sulphate polyacrylamide gel electrophoresis and adenosine triphosphatase assay in the presence of magnesium chloride. Ca2+ and K+ ethylenediaminetetra-acetic acid activated adenosine triphosphatase activities were determined in the presence of 3 mmol.litre-1 adenosine triphosphate. Myosin light chain subunits, VLC-1 and VLC-2, were analysed by polyacrylamide gel electrophoresis using: (i) sodium dodecyl sulphate at pH 7.0; (ii) 6 mol.litre-1 urea at pH 8.5; and (iii) isoelectric focusing in 9.2 mol.litre-1 urea over the pH range 4 to 6. No inherent differences in enzymic or physiochemical properties of the myosins from the human right and left ventricle were observed. Similar results were obtained in the baboon and dog.
Insights
Human ventricular myosin exhibits no significant differences between the right and left ventricles. This finding, observed in both human and animal models, suggests uniform myosin properties across the ventricles.
Area of Science:
- Cardiovascular Biology
- Molecular Physiology
- Biochemistry
Background:
- Myosin is a critical contractile protein in the heart.
- Understanding ventricular myosin properties is essential for cardiovascular research.
- Potential differences in myosin between cardiac ventricles are not well-established.
Purpose of the Study:
- To investigate potential differences in myosin properties between the human right and left ventricles.
- To compare enzymic and physiochemical characteristics of ventricular myosin.
- To validate findings across species.
Main Methods:
- Isolation and purification of myosin from human ventricular myocardium.
- Enzymatic assays for adenosine triphosphatase (ATPase) activity.
- Analysis of myosin light chain subunits using polyacrylamide gel electrophoresis and isoelectric focusing.
- Comparative analysis in baboon and dog models.
Main Results:
- Purified myosin showed negligible actin contamination.
- No inherent differences in Ca2+ and K+ EDTA-activated ATPase activities were observed between right and left ventricular myosin.
- Analysis of myosin light chain subunits (VLC-1, VLC-2) revealed no structural variations.
- Similar findings were replicated in baboon and dog ventricular myosin.
Conclusions:
- Human ventricular myosin from the right and left free walls shares identical enzymic and physiochemical properties.
- These findings suggest a conserved nature of ventricular myosin across different regions of the heart.
- The observed uniformity extends to other mammalian species, supporting conserved cardiac myosin function.