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。     

β—环糊精对苯丙氨酸解氨酶反应影响的研究

在含有较高浓度底物反式肉桂酸（ｔｒａｎｓ－ｃｉｎｎａｍｉｃ ａｃｉｄ,ＣＡ）和氨反应介质中,研究了β－环糊精（β－ＣＤ）对红醇母苯丙氨酸解氨酶（Ｐｈｅｎｙｌａｌａｎｉｎｅ ａｍｍｏｎｉａ－ｌｙａｓｅ,ＰＡＬ,ＥＣ４．３．１．５）催化反应的影响。加入适量β－ＣＤ可以克服高浓度ＣＡ对ＰＡＬ活性的抑制作用,显著增加产物Ｌ－苯丙氨酸（Ｌ－ｐｈｅ）的产量,β－ＣＤ最适用量随ＣＡ浓度升高而增加,其摩尔数量约为     

几种效应物对苯丙氨酸解氨酶稳定性的影响

为了对利用苯丙氨酸解氨酶（PAL）转化肉桂酸生成L-苯丙氨酸的生物转化反应条件进行优化,采用添加效应物的方法来提高苯丙氨酸解氨酶的稳定性,通过单因素实验研究了谷氨酸钠,海藻酸钠,聚乙二醇,甘油,锌粉,氮气等对PAL的稳定性影响,通过正交实验和方差分析,确定在转化液中添加1.0g/L锌粉和20g/L谷氨酸钠作为效应物,L-苯丙氨酸积累浓度提高55%,该两种效应物对PAL的稳定性增加显著。     

粘红酵母产L-苯丙氨酸解氨酶的条件和酶法合成苯丙氨酸的研究

研究了粘红酵母(Rhodotorula glutinis)中L-苯丙氨酸解氨酶(PAL)(EC4.3.1.5)的产酶条件及用此酶把反式肉桂酸转化成苯丙氨酸的条件.结果表明,在下列培养基(g/L)及培养条件下PAL的活力较高:酵母膏10.0,蛋白胨10.0,NaCl5.0,KH_2PO_4 0.5,苯内氨酸0.5,(NH_4)_2SO_41.0,葡萄糖5.0,pH6.0—6.5,培养温度为30℃.转化过程中,[NH_4~+]对初速度的影响符合米氏方程,其K_m和V_(max)分别为16.85mol/L和5.96 g·L~(-1)·h~(-1),最适pH为10.0.底物肉桂酸对反应初速度的影响,在低浓度时有激活作用,在高浓度下则有抑制作用.肉桂酸转化为苯丙氨酸的转化率在60.0%以上.     

水稻抗稻瘟病与苯丙氨酸解氨酶及过氧化物酶活性的相关性

已知苯丙氨酸解氨酶(PAL)和过氧化物酶(POD)与水稻抗稻瘟病有密切相关,水稻受到稻瘟病菌(Pyricularia oryzae)侵染时,体内PAL与POD活性会发生显著变化。本文采用30个水稻(Oryza sativa)品种为材料,选择经常规浸种、催芽、生长较一致的种子,每一品种     

百合鳞茎苯丙氨酸解氨酶提取条件的优化

研究兰州百合(Lilium davidii var. unicolor)鳞茎内PAL的最佳提取条件结果表明：pH 8.8的硼砂缓冲液为最适缓冲液;百合鳞茎的PAL不耐酸碱,更不耐酸;最适反应温度为40℃;随着水浴时间延长和水浴温度提高,PAL活性逐渐降低,但40℃水浴30 min后,酶活性仍保留47%;最适底物浓度为0.032 mol·L^-1;磨样时加入PVP 0.5 g,能够明显提高PAL活性。     

荞麦中苯丙氨酸解氨酶活力与黄酮含量的关系（简报）

荞麦幼苗及幼苗不同器官中的黄酮含量随着苯丙氨酸解氨酶(PAL)活力的变化而变化。X射线处理可增强荞麦幼苗中苯丙烷类代谢途径,致使黄酮含量提高。     

植物苯丙氨酸解氨酶基因的研究进展

苯丙氨酸解氨酶(phenylalanineammonia-lyase,PAL)是连接植物初级代谢和苯丙烷类代谢、催化苯丙烷类代谢第一步反应的酶。综述植物PAL基因的研究进展,主要包括PAL基因的结构特点、表达特点和PAL基因表达的调控机制,并指出今后对PAL基因的研究方向。     

大蕉苯丙氨酸解氨酶基因的克隆、鉴定和表达分析

为了研究苯丙氨酸解氨酶基因与大蕉(Musa ABB cv. Dongguandajiao)抗枯萎病的关系,利用 RT-PCR 和 RACE技术克隆了大蕉苯丙氨酸解氨酶基因全长 cDNA。此 cDNA 长 1 300 bp,包含一个长为 1 191 bp,编码 397 个氨基酸的完整开放阅读框(ORF),推导的氨基酸序列与水稻 PAL 基因氨基酸序列同源性达 89%,将此基因命名为 M-PAL。Southern杂交结果表明大蕉中存在一个包含 4-5 个 PAL基因的基因家族,将此基因克隆到大肠杆菌表达载体 pET32(a )中,表达的蛋白质分子量大小与推导的相一致,并且表达的蛋白质表现出 PAL 酶活性。对接种香蕉枯萎病菌 4 号生理小种(Fusarium oxysporumf. sp. cubense (FOC) race 4 )后大蕉叶片中 M-PAL基因的转录谱进行研究表明,在接种枯萎病菌后,M-PAL基因在叶片中的转录水平提高,因此推测 M-PAL基因的表达可能与香蕉枯萎病抗性相关。     

酵母细胞生物转化反式—肉桂酸生产L—苯丙氨酸的研究

据文献调查,搜集了国内可能相关的30株酵母,进行生物转化反式-肉桂酸(t-Ca) 生产L-苯丙氨酸 (L-Phe) 的微生物筛选研究,并对部分菌株生物转化能力,即苯丙氨酸解氨酶 (PAL,EC _(4、3、1、5) 活性水平进行了初步评估。筛选结果是:22株酵母具有转化 t-Ca 生成 L-Phe 的能力,转化率在2—67％范围。选出7株酵母研究在液体培养条件下细胞生长和PAL活性的时间过程关系,PAL 活性范围在 2.3—14.4x10~(-s)u/m g细胞干重。深红酵母 (Rhodotorularubra) AS2.166作为生物转化制备实经菌株,在静止细胞和固定化细胞批式反应条件下,结果获得L-Phe分离产率分别为42.0％,28.7％。     

ABA effects on ethylene production, PAL activity, anthocyanin and phenolic contents of strawberry fruit

Effects of exogenously applied abscisic acid (ABA) on ethyleneproduction rate, phenylalanine ammonia-lyase (PAL) enzyme activity, andanthocyanin and phenolic concentrations in harvested strawberry cv. Everestfruit were evaluated. Colouration and firmness were also assessed on fruit held for 3days at 20 °C. ABA treatment accelerated fruit colour andsoftening. Treatment with 10^–5 or 10^–4 mol ABAl^–1 stimulated ethylene production. Anthocyanin and phenoliccontents and PAL activity increased during storage, but more rapidly in ABAtreated fruit. As a result, red colour development was accelerated. EndogenousABA may play a role in strawberry fruit colour development during ripeningthrough up-regulation of ethylene production and PAL activity.     

Putative cis-elements in the promoter region of the carrot phenylalanine ammonia-lyase gene induced during anthocyanin synthesis

Deletion mutants of the carrot phenylalanine ammonia-lyase gene promoter were used to survey cis-elements for their effect on expression of promoter activity by transient expression. Two putative cis-elements were required to give full activity, but a third might be the most important in regulation of the promoter by 2,4-dichlorophenoxyacetic acid. Electronic Publication     

Accumulation of Pathogenesis-Related Proteins in Tobacco Leaves Irradiated with UV-B

Nicotiana tabacum L. (cv. Petit Havana SR1) were grown under ultraviolet-B (UV-B, 290–320 nm) irradiation, and soluble proteins were extracted from the leaves. Two-dimensional electrophoresis revealed that a minimum of 12 polypeptides were induced by UV-B. Polypeptides which were so abundant as to be detectable by Coomassie brilliant blue staining were then subjected to N-terminal amino acid sequence analyses. Two of the polypeptides were identified as a 23 kDa protein of PS II and 6 as a pathogenesis-related protein 5 (PR-5). Immunoblotting demonstrated that other PR proteins, PR-1 and PR-3 were also induced by UV-B. Salicylic acid (SA), which is an important component of signal transduction that leads to the expression of PR proteins and exhibition of acquired resistance to pathogens, increased in response to exposure to UV-B. In addition, the activity of phenylalanine ammonialyase, which catalyzes the synthesis from phenylalanine of trans-cinnamic acid, the endogenous precursor of SA, was transiently increased by UV-B irradiation. These results suggest that UV-B activates the signal transduction pathway, which is a common step in pathogen infection. Received 8 May 2000/ Accepted in revised form 29 August 2000     

Molecular characterization of the Bambusa oldhamii BoPAL3–encoded phenylalanine ammonia-lyase

Phenylalanine ammonia-lyase (PAL), which is ubiquitous in plants, catalyzes the formation of trans-cinnamic acid via the nonoxidative deamination of l-phenylalanine. Bambusa oldhamii contains four different forms of PAL proteins that differ in substrate specificity. Full-length BoPAL3 cDNA was cloned by a combination bamboo cDNA library screening and PCR-based cloning methods. Sequence alignment showed high homology between the deduced amino acid sequences of the BoPAL2 and BoPAL3 proteins (90%). Obvious PAL and tyrosine ammonia-lyase (TAL) activities were detected in Escherichia coli Top10 expressing recombinant BoPAL3 protein. Size-exclusion chromatography and denatured SDS–PAGE showed that the estimated molecular mass of recombinant BoPAL3 and the subunit form were approximately 330 kDa and 80 kDa, indicating that BoPAL3 presents as a tetrameric protein. The optimum temperature and pH for BoPAL3 activity were 50 °C and 8.5, respectively. The K_m value of BoPAL3 for l-phenylalanine was 200 μM.     

Interactions between parallel pathways during biosynthesis of rosmarinic acid in cell suspension cultures of Coleus blumei

Phenylalanine ammonia-lyase from an over-producer strain of Coleus blumei Benth. cell cultures accumulating high levels of rosmarinic acid (RA) has been shown to possess no special feed-back sensitivity to RA or its precursors. No tyrosine-3-hydroxylase activity could be detected in culture extracts and no specific inhibitors of tyrosine incorporation into RA were found. L--aminooxy--phenyl propionic acid, however, was effective in specifically blocking phenylalanine incorporation. This block also led to an accumulation of label from tyrosine in 4-hydroxyphenyllactic acid rather than in 3,4-dihydroxyphenylalanine (DOPA) or 3,4-dihydroxyphenyllactic acid. These observations require a re-evaluation of the possible role of DOPA as a major biogenic precursor to RA.Abbreviations AOPP -aminooxy--phenylpropionic acid - DOPA 3,4-dihydroxyphenylalanine - RA rosmarinic acid (-O-caffeoyl-3,4-dihydroxyphenyllactic acid) - PAL L-phenylalanine ammonia-lyase (EC 4.3.1.5)     

Mechanisms of inhibition of phenylalanine ammonia-lyase by phenol inhibitors and phenol/glycine synergistic inhibitors

Phenylalanine ammonia-lyase (PAL) catalyzes the beta-elimination of ammonia from L-phenylalanine to trans-cinnamic acid. A study of inhibition of PAL by phenol, ortho-cresol, and meta-cresol gave mixed inhibition; para-cresol is not an inhibitor. The calculated values of K(i) and alphaK(i) are phenol, K(i)=2.1+/-0.5 mM and alphaK(i)=3.45+/-0.95 mM; ortho-cresol, K(i)=0.8+/-0.2 mM and alphaK(i)=3.4+/-0.2 mM; meta-cresol, K(i)=2.85+/-0.15 mM and alphaK(i)=18.5+/-1.5 mM. The synergistic inhibition of the same inhibitors with glycine showed a lack of inhibition with the para-cresol/glycine pair, while mixed inhibition was observed with the ortho-cresol/glycine pair (K(i)=0.038+/-0.008 mM, alphaK(i)=0.13+/-0.04 mM) and phenol/glycine pair (K(i)=0.014+/-0.003 mM, alphaK(i)=0.058+/-0.01 M). The meta-cresol/glycine pair gave competitive inhibition (K(i)=0.36+/-0.076 mM). The strong synergistic inhibition observed implies that the inhibitors bind at the active site: in fact, the inhibitors used imitate the structure of the substrate. The order of synergistic inhibition is the same for the sites related to K(i) and alphaK(i). These results are in agreement with the inhibitors entering two active sites located in two different subunits.