Myosin adenosinetriphosphatase activity and light chain subunit composition of human right and left ventricle.

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.