title: Characterisation of human tear proteins using high-resolution mass spectrometry.
abstract: BACKGROUND
  The proteins found in tears play an important role in maintaining the ocular surface and changes in tear protein components may reflect changes in the health of the ocular surface. Proteomics provides a comprehensive approach for cataloguing all the proteins of the tear proteome, which will help to elucidate disease pathogenesis, make clinical diagnoses and evaluate the influence of medications on the structure, composition and secretion of tear proteins. In this study, an alternative proteomic strategy was investigated to explore the human tear proteome.
  
  
  METHODS
  Tear samples were obtained from patients who had pterygium and were collected on the first day and third day after pterygium surgery. Tears pooled from 6 patients were used in the analysis. Reverse-phase high-pressure liquid chromatograph (RPHPLC) was used as the first step to separate intact proteins into 21 peaks. Each fraction was then tryptic-digested and analysed by nanoLC-nano-ESI-MS/MS to characterise the protein components in each fraction.
  
  
  RESULTS
  In total, 60 tear proteins were identified with high confidence, including well-known abundant tear proteins, and tear-specific proteins such as lacritin and proline-rich proteins. Among them, proline-rich protein 5 was found for the first time in tear fluid. A large number of plasma proteins were also observed in tear fluid.
  
  
  CONCLUSIONS
  The results showed that the proteomic strategy used in this study was successfully applied to analyse tear proteome.
authors.affiliation: Singapore Eye Research Institute, Singapore.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Roger W
authors.initials: RW
authors.lastname: Beuerman
authors.forename: Yonghwee
authors.initials: Y
authors.lastname: Foo
authors.forename: Shouping
authors.initials: S
authors.lastname: Liu
authors.forename: Leonard P K
authors.initials: LP
authors.lastname: Ang
authors.forename: Donald T H
authors.initials: DT
authors.lastname: Tan
mesh_terms: D005136:Eye Proteins / Q000032:analysis*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D020543:Proteome; D013666:Tears / Q000737:chemistry*
chemical_list: D005136:Eye Proteins; D020543:Proteome; C042434:tear proteins