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几丁质酶(EC3.2.1.14)是一种降解几丁质的糖苷酶,广泛存在于各种生物体中,并在植物中对病原真菌起重要抗性作用。首先通过BLAST在GenBank中对其同源性进行搜索,用SMART分析其结构。基于水稻和拟南芥的基因组注释,借助4个生物学软件(SignalP3.0,TMHMM2.0,TargetP1.1andbig-PiPredictor),分析了水稻所有37条和拟南芥所有24条几丁质酶序列,发现有些几丁质酶都分泌到细胞外,有些定位于液泡中,水稻中仅25条和拟南芥中仅16条几丁质酶序列有信号肽,这些信号肽的平均长度为24.8aa。利用ClustalX和MEGA3.1两个生物软件分析了59条几丁质酶序列和25条标准几丁质酶的系统发育关系,这些几丁质酶可分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ和Ⅵ等6大类。这种聚类结果与几丁质酶传统分为7类有些差异。通过对6大类中各个氨基酸残基的分析,发现丙氨酸、甘氨酸、丝氨酸和亮氨酸的使用频率在每类中都非常高,而蛋氨酸、组氨酸、色氨酸和半胱氨酸均低于20%。各大类中彼此之间的某些氨基酸使用频率明显不同,Ⅰ-Ⅵ分别富含丙氨酸、缬氨酸、亮氨酸、半胱氨酸、丝氨酸和赖氨酸。
Chitinase (EC 3.2.1.14) is a chitinase degrading enzyme that is widely found in various organisms and plays an important resistance role in pathogenic fungi in plants. Its homology was first searched in GenBank by BLAST and the structure was analyzed by SMART. Based on the genome annotation of rice and Arabidopsis thaliana, all 37 rice lines and all 24 Arabidopsis thaliana chitinase sequences were analyzed using four biological softwares (SignalP3.0, TMHMM2.0, TargetP1.1andbig-PiPredictor) , And found that some chitinase are secreted to the extracellular and some are located in the vacuole. Only 25 of rice and only 16 of chitinase sequences in Arabidopsis have signal peptide, and the average length of these signal peptides is 24.8aa . The phylogenetic relationships of 59 chitinase and 25 standard chitinase were analyzed by two biological softwares, ClustalX and MEGA3.1. The chitinase could be divided into three groups: Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ and Ⅵ and other six categories. This clustering results and chitinase traditional divided into seven categories are some differences. By analyzing each of the six major classes of amino acid residues, the frequency of use of alanine, glycine, serine and leucine was found to be very high in each class, while methionine, histidine, tryptophan and cysteamine The acid is below 20%. The frequency of use of some of the amino acids in each of the major classes is significantly different, and I-VI are rich in alanine, valine, leucine, cysteine, serine and lysine, respectively.