A large variety of low molecular weight (LMW) peptides, derived from the breakdown of crystallins, have been reported in middle to old age human lenses. The proliferation of these LMW peptides coincides with the earliest stages of cataract formation, suggesting that the protein cleavages involved may contribute to the aggregation and insolubilisation of crystallins – these being hall marks of cataractogenesis. This study reports the identification of 238 endogenous LMW crystallin peptides from the cortical extracts of human lenses aged 16, 44, 75 and 83 years. Analysis of the peptide terminal amino acids showed that Lys and Arg were situated at the C-terminus with significantly higher frequency compared to other residues, suggesting that trypsin-like proteolysis may be active in the lens cortical fibre cells. Selected reaction monitoring (SRM) analysis of a prominent ?A-crystallin peptide (?A57-65) showed that the concentration of this peptide in the human lens increased gradually to middle age, after which the rate of ?A57-65 formation escalated significantly. Using 2-D gel electrophoresis and nanoLC-ESI-MS/MS, 13 protein complexes of 40-150 kDa consisting of multiple crystallin components were characterised from the water soluble cortical extracts of an adult human lens. The detection of these protein complexes suggested the possibility of crystallin cross-linking, with these complexes potentially acting to stabilise degraded crystallins by sequestration into water soluble complexes.
[dataset license: CC0 1.0 Universal (CC0 1.0)]
Keywords: Human lens ; crystallin ; endogeneuous peptidesLens aging ; crystallin ; cataract ; mass spectrometry ; endogenous peptides ; 2-D gel electrophoresis ; nanoLC-ESI-MS/MS ; trypsin-like cleavage
Principal Investigators: (in alphabetical order) |
Xiaomin Song, Australian Proteome Analysis Facility, N/A |
Submitting User: | ccms |
Su SP, Song X, Xavier D, Aquilina JA.
Age-related cleavages of crystallins in human lens cortical fiber cells generate a plethora of endogenous peptides and high molecular weight complexes.
Proteins. 2015 Oct;83(10):1878-86. Epub 2015 Aug 19.
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