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利用紫花苜蓿蛋白质二硫键异构酶(mPDI)的mRNA(来自NCBI,登录号为Z11499.1)及氨基酸序列(来自UniProtKB/Swiss-Prot数据库及NCBI数据库,其登录号分别为P29828、CAA77575.1),应用生物信息学软件预测了该蛋白质的理化性质、亲疏水性、信号肽、二级结构、卷曲螺旋结构、跨膜区域、糖基化位点、活性位点、亚细胞定位、功能结构域及高级结构。结果表明:紫花苜蓿mPDI蛋白质是一个整体疏水性蛋白,细胞定位为粗面内质网,含有512个氨基酸,理论等电点为4.98,分子量为57087.4Da,原子组成为C2597H3977N651O786S6,摩尔消光系数在280nm处为37610,不稳定系数为40.12,脂肪系数为79.96,总平均亲水性为-0.357。该蛋白质由20种氨基酸组成,其中非极性R基团氨基酸占44.3%,极性R基团氨基酸占28.4%,酸性氨基酸占13.6%,碱性氨基酸占13.1%,Lys、Glu、Val、Ala含量最为丰富,Met和Cys含量最少。信号肽位于1～24号氨基酸。利用ProtScale软件的KyteandDoolittle算法对mPDI蛋白进行亲/疏水性预测,结果表明该蛋白质含有7个高疏水性区域,分别分布在40～50区域、95～105区域、120～130区域、190～200区域、285～295区域、340～350区域以及365～375区域。利用SignalP网络工具对mPDI蛋白进行信号肽的预测,神经网络法显示第24～25位点是最可能的剪切点,马可夫模型显示了同样的信号肽酶切位点。mPDI蛋白质二级结构中α-螺旋占26.37%(135AA)、无规则卷曲占53.32%(273AA)、延伸链占20.31%(104AA);包含3个卷曲螺旋结构、3个糖基化位点(分别为143位的S、148位的T、461位的S)、2个硫氧还蛋白结构域(14～144位、357～485位)、2个硫氧还蛋白活性位点(54～72位、399～417位)、1个内质网靶向序列(509～512位);Ramachandram结构检测表明此模型的三维结构符合立体化学能量规则。
The mRNA (from NCBI, accession number Z11499.1) and amino acid sequence (from UniProtKB / Swiss-Prot database and NCBI database accession numbers of Medicago sativa protein disulfide isomerase (mPDI) are P29828, CAA77575 respectively. 1). Bioinformatics software was used to predict the physicochemical properties, hydrophilicity and hydrophobicity, signal peptide, secondary structure, coiled-coil structure, transmembrane region, glycosylation site, active site, subcellular localization and functional structure Domain and advanced structure. The results showed that the mPDI protein of alfalfa was an integral hydrophobic protein. The cell localization was rough endoplasmic reticulum and contained 512 amino acids. The theoretical isoelectric point was 4.98, the molecular weight was 57087.4Da, the atomic composition was C2597H3977N651O786S6, the molar extinction coefficient was 280nm 37610, instability coefficient of 40.12, fat coefficient of 79.96, the average hydrophilicity of -0.357. The protein consisted of 20 kinds of amino acids, including 44.3% of non-polar R group amino acids, 28.4% of polar R groups amino acids, 13.6% of acidic amino acids, 13.1% of basic amino acids, Lys, Glu, Val, Ala The most abundant content, Met and Cys content at least. The signal peptide is located on amino acids 1 to 24. The pro-hydrophobicity prediction of mPDI by Kyte and Doolittle algorithm of ProtScale software showed that the protein contained seven highly hydrophobic regions, which were distributed in 40-50 regions, 95-105 regions, 120-130 regions, 190-200 regions, respectively , 285 ~ 295 area, 340 ~ 350 area and 365 ~ 375 area. SignalP network tools for mPDI protein signal peptide prediction, neural network method shows that the first 24 to 25 sites is the most likely point of cleavage, Markov model showed the same signal peptide enzyme cleavage sites. The secondary structure of mPDI protein accounted for 26.37% (135AA), random coil accounted for 53.32% (273AA), extended chain accounted for 20.31% (104AA), contained three coiled-coil structures and three glycosylation sites 143 S, 148 T and 461 S, respectively), two thioredoxin domains (14144th and 357th ~ 485th), two thioredoxin active sites (54 ~ 72 and 399-417) and one endoplasmic reticulum targeting sequence (509-512). The structure of Ramachandram showed that the three-dimensional structure of this model was in accordance with the stereochemical energy rule.