荔枝果肉苯丙氨酸解氨酶特性的研究

Study on enzymology properties of L-phenylalanine ammonia-lyase(PAL) in litchi fruit

摘要: 研究了荔枝果肉中苯丙氨酸解氨酶（L-phenylalanine ammonia-lyase,PAL）的酶学特性。荔枝PAL动力学曲线并不遵循米氏方程,其最适底物浓度为2 mmol/L。在硼砂-硼酸缓冲液中,荔枝PAL的最适反应p H为8.7。PAL不耐酸碱,尤其不耐酸。荔枝PAL的最适反应温度为45℃,高于75℃则易于钝化,具有较强的耐热性。L-酪氨酸和L-半胱氨酸对荔枝PAL均有明显的抑制作用;金属离子中,Fe2+和Fe3+对荔枝PAL活性具有明显的促进作用,而Ca2+、Cu2+、Co2+、Ag+离子则对其活性有明显的抑制作用。

Abstract: The enzymology properties of L-phenylalanine ammonia-lyase(PAL) was investigated in this study.Litchi PAL dynamic curve did not follow the Michaelis-Menten equation. The optimum substrate concentration was 2 mmol/L. In the borax-boric acid buffer,the optimum reaction p H value was 8.7. Litchi PAL did not resistant to acid and alkali,especially to acid. The optimum reaction temperature was 45 ℃,and if the temperature was higher than 75 ℃,Litchi PAL was easily passivated. Litchi PAL had strong heat resistance. L-tyrosine and L-cysteine had significant inhibitory effect on Litchi PAL. Among the metal irons,Fe2+and Fe3+had significant promoting effect on PAL,while Ca2+,Cu2+,Co2+and Ag+had significant inhibitory effect on Litchi PAL.