血清多肽组及其个体差异的纳升液相色谱-高分辨串联质谱分析

Study of Human Serum Peptidome and Individual Difference by Nanoliter Liquid Chromatography-High Resolution Tandem Mass Spectrometry

分析和比较疾病组及健康对照组的混合样品是血清多肽组生物标记物研究的常用方法,但对健康个体多肽组的差异和共性关注较少。本研究利用纳升液相色谱-高分辨四级杆飞行时间质谱鉴定健康人混合血清样品(20例)的多肽组,阐明血清多肽组的分子量分布等一般特征,进而选取6例个体样品单独分析并与混合样品的分析结果进行比较,说明正常健康样品之间的个体差异和共同成分。结果表明,可鉴定序列的血清多肽组的分子量范围在7000 Da以下,纤维蛋白原α链等蛋白质所属肽段的检出频率最高,肽段在蛋白质水平上分布具有不均一性,排在前10%的蛋白质占据了约50%的总肽段,而后40%的蛋白质只有1条检出肽段。此外,在所有样品中都检测到了来自于8个蛋白质的12个共同肽段,检测到了N端乙酰化、氨基酸氧化、磷酸化、脱氨化和脱水等翻译后修饰和明显的阶梯序列现象。本研究在肽段序列水平分析了血清多肽组的基本特征和个体差异,可为血清多肽组生物标志物研究提供参考。

Peptidomic has become a common method of screening biomarkers,but most researches focused on the mixture samples by analyzing and comparing the results of samples from patients and healthy controls.Unfortunately,there is little study about the individual differences among healthy person and the common features of them.Here,to obtain the general characteristics of serum peptidomics including molecular weight distribution,nanoliter liquid chromatography-high resolution tandem mass spectrometry was used to analyze the mixture samples of 20 healthy human serums.Next,six cases of individual samples were analyzed and compared,indicating that there were obvious individual difference and some common features among different samples.We found that the peptides within 7000 Da could be identified and the peptides from fibrinogen α-chain were detected with the highest frequency.Additionally,the distribution of serum peptidome at protein level was heterogeneous;namely,the top 10% protein accounted about 50% of the total peptides and only one peptide was detected for the last 40% proteins.In addition,12 common peptides arising from 8 proteins were detected in all of the samples.Furthermore,the post-translational modification including N-terminal acetylation,oxidation,phosphorylation,deamination and dehydration,as well as the obvious sequence ladder phenomenon,were detected in all samples.In conclusion,the basic characteristics of peptidomics at the sequence level were explored and the individual difference of serum peptidome was proposed,which could provide a reference for the study of serum peptide biomarkers.