长双歧杆菌NCC2705菌株应激蛋白的研究

研究长双歧杆菌NCC2705菌株发酵至稳定期时应激蛋白的表达情况。根据乳酸乳球菌IL1403菌株蛋白质参考图谱及长双歧杆菌NCC2705基因组注释中应激蛋白的分子量与等电点,确定应激蛋白在双向电泳凝胶上的相应蛋白点,并利用MALDI-TOF和/或ESI-MS/MS对相应蛋白质点进行鉴定。每个蛋白质点的肽指纹图谱均在长双歧杆菌NCC2705的蛋白质数据库用Mascot进行检索,共鉴定到44个蛋白点对应8个应激蛋白。这些蛋白为亲水性酸性蛋白,大多具有翻译后修饰现象,它们基因的CAI值除DnaJ外,其余均在0.5以上,在全细胞表达谱中为高丰度蛋白;此外,菌体具有较强的抗脂质过氧化和清除DPPH自由基的能力,而对羟自由基和超氧负离子的清除力较弱,推测鉴定到的具有逆转氧化损害作用的碱性过氧化氢还原酶(ahpC)可能是体内表达的降低氧损伤的主要酶。

Stress proteins of Bifidobacterium longum NCC2705

Stress proteins of Bifidobacterium longum strain NCC2705 were identified and characterized during stationary phase.According to the proteomic map of L.lactics IL1403 and theoretical Mr/pI of stress proteins in B.longum NCC2705 genome annotation,spots of stress proteins in gels were localized,and proteins were identified by matrix-assisted laser desorption/ionization time of flight (MALDI-TOF)and/or ESI-MS/MS mass spectrometry.For protein identification by peptide mass fingerprinting,peptide masses were searched against database of B.longum NCC2705 by Mascot licensed in-house.44 spots representing 8 protein entries have been identified,these proteins were hydrophilic proteins and predicted acid proteins.Spot and protein analysis revealed that post-translational modifications might be common in these proteins.Except for DnaJ,the stress proteins were encoded by genes with CAI value above 0.5,and represented a large proportion of the most abundant proteins.Moreover,the results of scavenging effects on free radicals in vitro showed that B.longum NCC2705 can inhibit fatty acid oxidation and scavenge DPPH,but they scavenge weakly active oxygen free radicals.We identified a key protein that can reverse oxidative damage to proteins and lipids: alkyl hydroperoxide reductase(ahpC,BL0615)synthesized under our experimental conditions.