Dissociation of natural actomyosin from kuruma prawn muscle induced by pyrophosphate

Effect of pyrophosphate (PP) on the dissociation and stability of natural actomyosin (NAM) from kuruma prawn muscle was studied in comparison with adenosine 5′-triphosphate (ATP). In the presence of PP up to 5 mM, NAM exhibited lower Mg2+-ATPase activity (P < 0.05), while no marked change was observed in NAM treated with ATP at all concentrations tested (0.25–10 mM) (P > 0.05). Ca2+-ATPase activity of NAM treated with 5 mM PP decreased markedly when incubated at temperatures greater than 30 °C, suggesting lowered thermal stability of the liberated myosin molecule. Nevertheless, Ca2+-ATPase activity of ATP-treated NAM was similar to the control NAM. In the presence of 5–10 mM MgCl2, NAM treated with 5 mM PP underwent dissociation effectively, as evidenced by a greater decrease in Mg2+-ATPase activity as well as an increased band intensity of actin released. Therefore, addition of PP in combination with MgCl2 was more effective than was ATP in dissociating the actomyosin complex of prawn muscle.