Characterization of two putative prolinases (PepR1 and PepR2) from Lactobacillus plantarum WCFS1: Occurrence of two isozymes with structural similarity and different catalytic properties
作者:Yanyu Huang、Takuji Tanaka
DOI:10.1016/j.bbapap.2014.11.003
日期:2015.2
amino acid sequence identity (55.5% at the DNA level); however, PepR1 exhibits over 80% identity at the protein level with other lactobacilli prolinases while PepR2 exhibits only 51% or less identity. In this study, the putative genes were overexpressed in Escherichia coli, purified to gel electrophoretic homogeneity, and then characterized. Purified PepR1 and PepR2 hydrolysed Pro-Xaa dipeptide substrates
植物乳杆菌WCSF1的两个推定的脯氨酸蛋白酶(PepR1和PepR2)具有48.5%的氨基酸序列同一性(在DNA水平上为55.5%);然而,PepR1在蛋白质水平上与其他乳酸杆菌脯氨酸酶的同一性超过80%,而PepR2仅在51%或更少的同一性。在这项研究中,推定的基因在大肠杆菌中过表达,纯化至凝胶电泳均质,然后进行表征。纯化的PepR1和PepR2以相似的速率水解Pro-Xaa二肽底物,证明了它们作为脯氨酸酶的性质。使用圆二色性,动态光散射,凝胶过滤和分子模型进行的结构分析显示,两种蛋白酶均具有相似的结构特征:高β-折叠含量,同四聚体结构以及与PepI / PepL / PepR肽酶家族相似的折叠。然而,PepR1和PepR2的动力学和热力学分析表明,在许多方面存在差异:最佳温度(分别为25和30°C),最佳pH(分别为pH7.5和8.0),底物特异性(PepR2的高严格性),动力学参数,