Effect of carnosine on steroid-induced modification of lens α-crystallin / 国际眼科杂志(Guoji Yanke Zazhi)

ABSTRACT

AIM: To explore whether carnosine can protect α -crys-tallin modification and decreased chaperone by a steroid,and whether carnosine could directly react with a steroid.METHODS: Bovine lens α L-crystallin was separated by size-exclusion chromatography on a Sephacyl S-300 HR column. α L-Crystallin was incubated with different concentrations of prednisolone-21-hemisuccinate (P-21-H)with or without carnosine for different times. The chaperone activity of α L-crystallin was monitored using the prevention thermal aggregation of α L-crystallin. The modified α L-crystallinwas examined by SDS-PAGE and fluorescence measurements. The absorbance spectra of solutions of carnosine and P-21-H were investigated.RESULTS: P-21-H decreased the chaperone activity ofα L-crystallin in a concentration- and time-dependent fashion. Carnosine only worsened this effect. The tryptophan fluorescence intensity of α L-crystallin modified by P-21-H was significantly decreased compared to unmodified crystallin, whereas its non-tryptophan fluorescence was increased with a shift to longer wavelengths in a time- and dose-dependent manner, suggesting that new fluorophores are possibly formed. Carnosine readily reacted with P-21-H thereby inhibiting steroid-mediated protein modification as revealed electrophoretically. The increased absorbance was time-dependent, suggesting adducts may be formed between carnosine and P-21-H.CONCLUSION: Carnosine reacts with P-21-H, which suggests carnosine's potential as a possible anti-seroid agent.