人唾液蛋白质组的纳升液相色谱-高分辨串联质谱鉴定及高丰度蛋白质分析

Proteomic Identification and High Abundant Proteins Analysis of Human Saliva by Nano-Liquid Chromatography-High Resolution Tandem Mass Spectrometry

  • 摘要: 常规的定性分析质谱数据能否以及如何应用于蛋白质组学的相对定量分析是实际工作中经常遇到的问题。本研究采用一维纳升液相色谱-高分辨串联质谱(nano-HPLC-Triple TOF 5600)法鉴定人唾液蛋白质组,并分析其基本组成,以探讨质谱数据与唾液中高丰度蛋白质的相关性。本实验共鉴定了6044条特异性酶切肽段,归属于α-淀粉酶1、碳酸酐酶6、血清白蛋白、粘蛋白、半胱氨酸蛋白酶抑制剂和免疫球蛋白等各种已知的高丰度蛋白质在内的521个蛋白,这为一维纳升液相色谱分离条件下的唾液蛋白质组的基本组成分析提供了参考。结果表明,仅用蛋白质排序指标Unused值表征蛋白质的相对含量具有局限性,而蛋白质排序、检出肽段数目和肽段平均强度等综合指标与蛋白质相对含量具有正相关性,即排名较后的蛋白质均只有1条肽段被检出,且肽段强度较低。这说明,当蛋白质相对含量差别较大时,肽段的化学性质和电离效率差异对质谱信号的影响已不占主要地位,即可以认为当肽段检出数目、鉴定覆盖率和肽段强度均较低时,蛋白质的相对含量也较低。该结果可为利用Triple TOF 5600质谱仪的定性鉴定数据进行初步半定量判断提供参考,也可为唾液蛋白质组生物标志物研究提供借鉴。

     

    Abstract: In mass spectrometry-based proteomics, one of the most common problem is whether and how to apply the mass spectrum data of qualitative analysis for the relative quantitative analysis, because not only there is interest for making full use of the data but also there is a demand in practical work. In this study, nano flow high performance liquid chromatography-high resolution tandem mass spectrometry (nano-HPLC-Triple TOF 5600) was used to analyze the basic components of the human saliva proteome, furthermore, the relationship between the mass spectrum data and the high abundant proteins in saliva was discussed. A total of 6 044 specific enzyme peptides arising from 521 proteins were identified, in which α-amylase 1, carbonic anhydrase 6, serum albumin, mucin and several kinds of cystatin et al were identified as high abundant proteins. This study provided a basic reference for the component of saliva proteome based on the one-dimensional HPLC-MS/MS method. In addition, the result showed that although the Unused value is the most important parameters to measure the reliability of qualitative analysis protein, only using Unused value to stand for the relative abundance of proteins is not suitable. Fortunately, there is a positive correlation among the combination of the protein rank (Unused value), the number of peptides detected as well as the average intensity of peptides and the relative contents of protein. For example, for those of proteins whose Unused value is low, which only one peptide is detected and the intensity of peptides is also low. Namely, this result indicated that when the relative contents of protein is very different, the chemical properties and ionization efficiency of peptides are not the main parameters to affect the signal intensity. In other words, the low number of peptides detected combined with the low signal intensity indicated the content of protein is low. This result is helpful for evaluating the relatively quantitative composition of human saliva by using Triple TOF 5600 mass spectrometer and for the research on saliva proteome biomarkers.

     

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