Lim H W, Sa J H, Park S S, Lim C J
Division of Life Sciences, College of Natural Sciences, Kangwon National University, Chuncheon, Korea.
Mol Cells. 1998 Jun 30;8(3):343-9.
Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) catalyzes the elimination of ammonium ion from L-phenylalanine in a variety of plants and fungal species. PAL was previously purified and characterized from leaf mustard in our laboratory. In the present study, we purified a second phenylalanine ammonia-lyase (PAL II) from leaf mustard by a combination of ion exchange chromatography and gel filtration. PAL I and PAL II migrate at a different rate on native polyacrylamide gel electrophoresis. It consists of four subunits, each having the molecular mass of about 37,000 Da. Its isoelectric point and Km value for L-phenylalanine were found to be 5.4 and 3.8 x 10(-5)M, respectively. The purified enzyme has an optimum pH and temperature of 8 and 45 degree C, respectively. It is activated about 2-fold by caffeic acid (1 mM), whereas it is inhibited to 15% by Zn2+ (1 mM). However, the physiological role of PAL II remains unknown.
苯丙氨酸解氨酶（PAL，EC 4.3.1.5）在多种植物和真菌物种中催化从L-苯丙氨酸中去除铵离子。之前我们实验室已从叶用芥菜中纯化并鉴定了PAL。在本研究中，我们通过离子交换色谱和凝胶过滤相结合的方法从叶用芥菜中纯化出了第二种苯丙氨酸解氨酶（PAL II）。PAL I和PAL II在非变性聚丙烯酰胺凝胶电泳上的迁移速率不同。它由四个亚基组成，每个亚基的分子量约为37,000 Da。发现其L-苯丙氨酸的等电点和Km值分别为5.4和3.8×10⁻⁵M。纯化后的酶的最适pH值和温度分别为8和45℃。它被咖啡酸（1 mM）激活约2倍，而被Zn²⁺（1 mM）抑制至15%。然而，PAL II的生理作用仍然未知。
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