Oxidative modification of rat eye lens proteins by peroxyl radicals in vitro: protection by the chain-breaking antioxidants stobadine and Trolox.
In an attempt to model the processes of free radical-mediated cataractogenesis, we investigated the oxidative modification of rat eye lens proteins by peroxyl radicals generated by thermal decomposition of 2,2'-azobis(2-amidinopropane)hydrochloride (AAPH) under aerobic conditions. When incubated with AAPH, the soluble eye lens proteins precipitated in a time-dependent manner. The insolubilisation was accompanied by the accumulation of protein free carbonyls and the diminution of sulfhydryls, yet the processes were shifted in time. The SDS-PAGE analysis of the AAPH-treated proteins revealed the presence of high molecular weight cross-links and, to a lesser extent, fragments. The aggregation and cross-linking of proteins along with the generation of free carbonyls was significantly inhibited by the chain-breaking antioxidants stobadine and Trolox. On the other hand, the AAPH-initiated sulfhydryl consumption was much less sensitive to the antioxidants studied. The results point to a complex mechanism of peroxyl-radical-mediated modification of eye lens proteins with implications for cataract development and they indicate a potentially protective role of antioxidants.
Stefek
M
M
Institute of Experimental Pharmacology, Slovak Academy of Sciences, Dubravska cesta 9, 841 04 Bratislava, Slovakia. exfastfk@savba.sk
Kyselova
Z
Z
Rackova
L
L
Krizanova
L
L
D000332:Aerobiosis; D000578:Amidines / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002243:Carbolines / Q000494:pharmacology*; D002386:Cataract / Q000209:etiology; D002839:Chromans / Q000494:pharmacology*; D003459:Crystallins / Q000378:metabolism*; D005609:Free Radicals / Q000378:metabolism; D020128:Inhibitory Concentration 50; D008297:Male; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D010545:Peroxides / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012995:Solubility / Q000187:drug effects; D013696:Temperature; D013997:Time Factors
D000578:Amidines; D000975:Antioxidants; D002243:Carbolines; D002839:Chromans; D003459:Crystallins; D005609:Free Radicals; D016877:Oxidants; D010545:Peroxides; C049375:perhydroxyl radical; C046728:2,2'-azobis(2-amidinopropane); C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; C100106:dicarbine