Abstract

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 MgCl<inf>2</inf>, 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 MgCl<inf>2</inf> was more effective than was ATP in dissociating the actomyosin complex of prawn muscle. © 2006 Elsevier Ltd. All rights reserved.