苯丙氨酸解氨酶

苯丙氨酸解氨酶由四个亚基组成,含两个脱氢丙氨酸残基。植物酶具有内在不稳性,由多种同工酶组成。酶催化过程中发生构象变化,底物经过负碳离子中间体完成反应。该酶并非是二单体负协同变构酶。一级结构表明,酶以无规则卷曲结构为主。酵母基因约2.7kb,有六个内含子,编码75kD_a肽。植物酶由多基因编码,有一个内含子,编码78kD_a肽。启动子部位有两个富含A、C碱基的序列,为胁迫作用基因活化因子结合部位。

PHENYLALANINE AMMONIA-LYASE

Phenylalanine Ammonia-ly.ase(PAL,EC4.3.1.5)is conposed of four subunits and contain two dehydroalanine(DHA)residues in whole enzyme protein as prothetic groups in catalysis. Many isoenzymes exist in plant which seem to be inheritable instable in vivo and in vitro. The enzyme has been proposed to be induced by corn bination of the correspondying substrates to adopt a correct conformation which could effect the reaction of them via a carboanion intermediate. The two-promoter negative concerted catalytic model are considered not to be true for the enzyme at present. The methods are avaiable to isolate and purify the inzyme from various sources, the comparision of PAL amino acids sequences from rhqdotorula rubra, rhodosporidium toruloides,petroselinum crispum, phaseoylus vulgaris,and genes structure and organization are also respectivily reviewed here.