Effects of Temperature,pH and Metal Ions on Invertase Activities in Different Fruits

Effects of temperature,pH and metal on soluble acid invertase,soluble neutral invertase and cell wall-bounded invertase were studied in apple,pear and peach fruit.The results showed that the optimum temperature for acid invertase activity was 40 ℃,but that for neutral invertase activity was 50 ℃.The best pH for acid invertase activity was about 5,and that for neutral invertase activity was 7 or so.The results also showed that the activities of invertase were significantly enhanced by Mn2+ and Ca2+;Moreover,Cu2+,Mg2+ and Zn2+ also increased the activities of acid invertases.The activity of soluble neutral invertase was partially inhibited by Cu2+,Mg2+ and Zn2+,while the activities of all three isoforms of invertase were significantly inhibited by Hg2+.The function of invrtases in sugar metabolism was discussed in relation with fruit development and quality formation.