Study of Characteristics and Distribution Patterns of Human Serum Peptidome Based on High Resolution Tandem Mass Spectrometry
Research on serum peptidome biomarkers typically involves comparing the relative abundance of peptides in different samples,but the distribution characteristics of the human serum peptidome has not yet been reported.In this study,a high resolution tandem mass spectrometry(HPLC-MS/MS)method was used for analysis of serum peptidome from 50 volunteers to compare and summarize the number of the identified peptides and their attributed proteins,peptide intensities,and peptidomics characteristics,and to explore the distribution pattern of the serum peptidome.The results showed that the distributions of the peptide at the protein level were significant heterogeneous,namely,the top 20%of dominantly degraded proteins occupied about 78%of the total peptide number and about 85%of the total peptide intensity,whereas only one peptide could be detected for those of last 40%protein.Additionally,the number of peptides detected in serum samples was positively correlated with the number of degraded proteins to which they were attributed,and a range of peptides with similar molecular mass but different sequences were present in the serum peptidome.Moreover,by using a variety of degraded proteins such as thymosin β4,complement C3 and fibrinogen alpha chain as examples,it was found that a series of relatively concentrated and consecutive enzyme cleavage sites always existed in dominantly degraded proteins,and that the resulting series of stepped-sequence or correlated-sequence peptides were responsible for the heterogeneous distribution of peptides in the peptidome.Finally,the absolute signal intensities of individual degraded peptides were found to vary considerably across samples,even up to one hundred-fold or more,but some peptides with higher signal intensities were found to be relatively stable across samples,and they had also been frequently reported as disease biomarkers.The distribution patterns and characteristics of these serum peptidome might not only provide new references for biomarker selection criteria,but also could be used for methodological quality evaluation during separation and mass spectrometry analysis.
PeptidomeSerumDistribution patternBiomarkerHigh resolution tandem mass spectrometry
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