Carnosine ameliorates lens protein turbidity formations by inhibiting calpain proteolysis and ultraviolet C-induced degradation

Jiahn Haur Liao, I. Lin Lin, Kai Fa Huang, Pei Ting Kuo, Shih Hsiung Wu, Tzu Hua Wu

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Carnosine (CAR) is an endogenous peptide and present in lens, but there is little evidence for its effectiveness in calpain-induced proteolysis inhibition and its differential effects toward different wavelengths of ultraviolet (UV) irradiation. This study aimed to develop three in vitro cataract models to compare the mechanisms underlying the protective activities of CAR. Crude crystallins extracted from porcine lenses were used for antiproteolysis assays, and purified γ-crystallins were used for anti-UV assays. The turbidity in those in vitro models mimics cataract formation and was assayed by measuring optical density (OD) at 405 nm. The effectiveness of CAR on calpain-induced proteolysis was studied at 37 and 58°C. Patterns of proteins were then analyzed by SDS-PAGE. The turbidity was reduced significantly (p <0.05) at 60 min measurements with the increased concentration of CAR (10-300 mM). SDS-PAGE showed that the decreased intensities at both ∼28 and ∼30 kDa protein bands in heat-enhanced assays were ameliorated by CAR at ≥10 mM concentrations. In UV-B studies, CAR (200, 300 mM) reduced the turbidity of γ-crystallin significantly (p <0.05) at 6 h observations. The turbidity of samples containing γ-crystallins was ameliorated while incubated with CAR (100, 300 mM) significantly (p <0.05) following 4 h of exposure to UV-C. SDS-PAGE showed that the presence of CAR reduced UV-B-induced aggregation of γ-crystallins at ∼44 kDa and resulted in less loss of γ-crystallin following UV-C exposure. The result of modeling also suggests that CAR acts as an inhibitor of calpain. In conclusion, CAR protects lens proteins more readily by inhibiting proteolysis and UV-C-induced degradation than aggregation induced by UV-B irradiation.

Original languageEnglish
Pages (from-to)5932-5938
Number of pages7
JournalJournal of Agricultural and Food Chemistry
Issue number25
Publication statusPublished - Jun 25 2014


  • UV insults
  • calpain proteolysis
  • carnosine
  • lens turbidity
  • molecular modeling

ASJC Scopus subject areas

  • General Chemistry
  • General Agricultural and Biological Sciences


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