尿液多肽组的时间可变性和相对稳定性研究

All the peptides in the urine is peptidome , which can reflect the pathological changes of the body , thereby providing potential biomarker information. At present, morning urine is most often used in the research of urinary peptidomics. However, whether its composition changes with the sampling time is not clear. In this study , the urine samples from the three healthy people at different time points were separated by the graphene oxide-lanthanum phosphate nanocomposite (LaGM) method and identified by LC-MS/MS. Protein Pilot Software 4. 5 was used for database search and analysis. It was found that the peptides and proteins of urine at each time point of the same person were different, which was reflected in the change of number and sequence of peptides in high-abundance degraded proteins and "with" or "without" in low-abundance. The number of peptides detected in urine significantly increased by sampling a plurality of times in a day. On the other hand , the peptidomics was also certain stable. The degradation peptides SGSVEDQSRVLNLGPITR of uromodulin not only existed at every time point but also had higher relative strength than other sequence-related peptides. Collagen was the dominant component in morning urine (urine at 6 o'clock) . Further more , the result was verified by single urines , mixed urines of different ages , and literature data. This study showed that the sampling time was the main influencing factor of urinary peptidomics. The 24-h urine samples would be more suitable 14 sample than the morning urine. Due to the existence of the ladder sequence and the influence of individual differences , the absolute signal intensity of peptide should not be used for direct comparison between different samples and the selection of biomarkers.