Isolation and partial characterisation of bovine rumen myosin

Myosin was isolated from rumen muscle and purified by DEAE Sephadex A-50 chromatography. The purified myosin gave only two bands on SDS gel electrophoresis, one corresponding to the heavy chain of 210 000 D and the other corresponding to a light chain of 17 000 D. The pH optimum of the rumen myosin ATPase activity was found to be at 7·6; and at pH 9·1, there was no detectable activity. The ATPase activity of the rumen myosin was found to be lower than that of the skeletal myosin. Since it is known that the light chains are located on the globular head of the myosin molecule, where the ATPase activity is found, the lower rumen myosin ATPase activity may be due to the absence of certain light chains that are commonly found in the skeletal myosin. The rumen myosin also had a lower basic amino acid content and a lower ratio of basic to acidic amino acids than the corresponding skeletal muscle counterpart.