Abstract
Comparative biochemical studies on highly purified myosins from dorsal muscle of carp, Cyprinus carpio, and tilapia, Tilapia mossambica, and skeletal muscle of rabbit were performed.
The following biochemical properties were investigated: chromatographic profile on DEAE-Sephadex column, effects of Ca2+, Mg2+, EDTA, and PCMB on myosin ATPase activity, sulfhydryl group content, and thermo-stability of Ca2+-ATPase activity.
1) The elution profiles of fish myosins at 280 mμ were very similar to that of rabbit monomeric myosin.
2) The influences of various effectors such as KC1, Ca2+, Mg2+, EDTA, and PCMB on fish myosin ATPase activity were essentially the same as those on rabbit myosin.
3) The sulfhydryl group contents of carp and tilapia myosins were found to be 31-34 and 33-35 moles/5 ×105g of protein, respectively.
4) The most striking differences between fish and rabbit myosins were observed in thermo-stability of Ca2+-ATPase activity. In 0.6 M KCl the rates of inactivation of the myosins from carp, tilapia, and rabbit at pH 7.0 and 30°C were found to be 61.1×10-5 sec-1, 18.3×10-5 sec-1, and 5.0×10-5 sec-1, respectively. Approximately fifty percent loss of Ca2+-ATPase activity of carp, tilapia, and rabbit myosins was obtained on incubation for 15min at 28°C, 32°C, and 36°C, respectively.
