目的 用生物信息学方法分析刚地弓形虫苹果酸脱氢酶(TgMDH)基因编码蛋白的结构与抗原表位,预测该蛋白的免疫原性.方法 利用蛋白分析专家系统(ExPASy)提供的ProtParam、SOSUI、TMPRED、HNN、MotifScan和NCBI上的ORF finder、SignalP、Bcepred等生物信息学在线分析程序,结合Gene Runner和DNAMAN等生物信息学软件,分析并预测TgMDH蛋白的开放阅读框、理化性质、可溶性、信号肽、跨膜区、表面可及性、可塑性、亲(疏)水性、翻译后修饰位点、二级结构及抗原表位,通过CPHmodels程序预测该蛋白的三维空间结构.结果 TgMDH蛋白由316个氨基酸组成,分子式为C1498H2454N402O440S20,分子质量单位为33 777.5,等电点为6.01,波长280 nm时的吸光度(A)值为0.364,半衰期为30 h,有9个表面可及性参数≥1.9的区域、4个亲水性参数得分≥1.9的区域、7个柔韧性参数得分≥2的区域、14个翻译后修饰位点和14个潜在抗原表位,为可溶性表达蛋白.结论 TgMDH基因编码蛋白为可溶性蛋白,有多个抗原表位,具有免疫原性,可作为弓形虫病疫苗候选抗原.%The immunogenicity of the malate dehydrogenase protein extracted from Toxoplasma gondii (TgMDH) was predicted and its structure and epitopes were characterized by bioinformatics approaches. The open reading frame, physico-chemical properties, solublity, signal peptide, cross membrane area, surface accessibility, flexibility, hydrophilicity, post-translational modification site, secondary structure, and antigen epitope of TgMDH protein were analyzed and predicted by bioinformatics online analysis programs which were provided by expert protein analysis system (ExPASy) including Prot-Param, SOSUI, TMPRED, HNN, MotifScan, ORF finder, SignalP and Bcepred, combining with bioinformatics softwares (Gene Runner and DNAMAN). The three dimensional structure of the protein was then processed by CPHmodels. Results indicated that TgMDH protein was composed of 316 amino acids with listed characters: the molecular formula was C149852454 N402 O440S20, the molecular mass was 33 777. 5, the value of theoretical isoelectric point was 6. 01, the absorbance (A280) value was 0. 364 , and the half-life period was 30 h. There were nine zones with surface accessibility≥1. 9 , four zones with hydrophilicity ≥1. 9, seven zones with flexibility≥2, fourteen post-translational modification sites and fourteen potential epitopes as soluble protein expression. It's suggested that TgMDH protein could be used as a candidate antigen for toxoplasmosis vaccination because of its soluble protein expression and immunogenic property.
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