Study on the tripolyphosphatase (TPPase) of myofibrils from Aristichthys nobilis muscle

The hydrolysis of sodium tripolyphosphate (STPP) in the fresh Aristichthys nobilis minced meat and myofibrils (Mf) were studied by using ion chromatog raphy (IC). The results showed that STPP was hydrolyzed to pyrophosphate（PP）and orthophosphate(Pi), whereas pyrophosphate was further hydrolyzed to orthophosphate in Aristichthys nobilis minced meat. In the case of myofibrils, STPP was also hydrolyzed to pyrophosphate and orthophosphate. Myofibrils from Aristichthys nobilis muscle had the activity of tripolyphosphatase (TPPase). The optimum temperature and pH for the TPPase activity of myofibrils from Aristichthys nobilis muscle were 25 ℃，pH 5.5.The TPPase activity of myofibrils was activated at the condition of below 5 mmol·L^-1 Mg²⁺, but was inhibited when the content of Mg²⁺ over 5 mmol·L-1. At the condition of 0.3 mol·L^-1 KCl, the strongest activity was determined at 5 mmol·L^-1 Mg²⁺. The TPPase activity of myofibrils from Aristichthys nobilis was also affected by KCl. The optimum consistence of KCl for the TPPase was 0.3 mmol·L^-1 at the condition of 5 mmol·L^-1 Mg²⁺. EDTA-Na₂ could inhibit activity of TPPase.