温度、pH和金属离子对不同果实转化酶活性的影响

为国果实转化酶的分离纯化提供参考依据,研究了温度、pH和金属离子对苹果、梨和桃中可溶性酸性转化酶、可溶性中性转化酶和细胞壁结合转化酶。活性的影响结果表明,酸性转化酶的最适反应温度为40℃,而中性转化酶为50℃;酸性转化酶的最适pH在5左右,中性转化酶的最适pH在7左右。金属离子Mn2+和Ca2+显著提高3种转化酶的活性,而Cu2+,Mg2+和Zn2+也在一定程度上提高可溶性酸性转化酶和细胞壁转化酶的活性;Hg2+显著抑制3种转化酶活性,而Cu2+,Mg2+和Zn2+抑制可溶性中性转化酶的活性,表明转化酶的活性部位含巯基基团。对转化酶特性与苹果、梨和桃果实发育和品质形成的关系进行了讨论。

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 Mn^2＋ and Ca^2＋;Moreover,Cu^2＋,Mg^2＋ and Zn^2＋ also increased the activities of acid invertases.The activity of soluble neutral invertase was partially inhibited by Cu^2＋,Mg^2＋ and Zn^2＋,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.