title: Screening High Abundance of Peptide for Making Examination Possible in Human Urine.
abstract: OBJECTIVE
  We aim to explore and identify the high abundance of peptides in urine.
  
  
  METHODS
  Random urine samples from 30 healthy individuals were purified by weak cationic-exchange magnetic beads (MB-WCX) and then analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Then the generated mass spectra of peptides were handled by ClinPro-Tools2.1 bioinformatics software and the high abundance of urinary peptide was filtered. Subsequently, the amino acid sequences of highly expressed peptides were identified by a nano-liquid chromatography-tandem mass spectrometry and the corresponding protein names were found by Sequest search.
  
  
  RESULTS
  There were 159 urinary peptides of which mass to charge ratios (m/z) varied between 1,000 and 10,000 in the 30 healthy samples. Only peaks with average intensity >600 and the frequency >50% in the whole group were filtered. There were 15 peptides passed though the threshold and they were identified as fragments of fibrinogen alpha chain precursor, vitronectin precursor, inter-alpha-trypsin inhibitor heavy chain H4, complement component 3, prothrombin, apolipoprotein C-II, and alpha-fetoprotein.
  
  
  CONCLUSIONS
  These urinary peptides could be used for further research on urine.
authors.affiliation: Department of Clinical Laboratory, Peking University Ninth School of Clinical Medicine, Beijing Shijitan Hospital, Haidian District, Beijing, China.
authors.forename: Guangzhen
authors.initials: G
authors.lastname: Fu
authors.affiliation: Department of Clinical Laboratory, Peking University Ninth School of Clinical Medicine, Beijing Shijitan Hospital, Haidian District, Beijing, China.
authors.forename: Na
authors.initials: N
authors.lastname: Liu
authors.affiliation: Department of Clinical Laboratory, Peking University Ninth School of Clinical Medicine, Beijing Shijitan Hospital, Haidian District, Beijing, China.
authors.forename: Lina
authors.initials: L
authors.lastname: Chu
authors.affiliation: Department of Clinical Laboratory, Peking University Ninth School of Clinical Medicine, Beijing Shijitan Hospital, Haidian District, Beijing, China Department of Clinical Laboratory, Beijing Shijitan Hospital, Capital Medical University, Haidian District, Beijing, China mzhang99@aliyun.com.
authors.forename: Man
authors.initials: M
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000652:urine*; D040901:Proteomics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D010455:Peptides
keywords: MALDI-TOF MS; Urinary internal standards; Urinary peptides