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  • Title: Methylglyoxal inhibits glycation-mediated loss in chaperone function and synthesis of pentosidine in alpha-crystallin.
    Author: Puttaiah S, Biswas A, Staniszewska M, Nagaraj RH.
    Journal: Exp Eye Res; 2007 May; 84(5):914-21. PubMed ID: 17368444.
    Abstract:
    Alpha-crystallin is a major protein in the eye lens and it functions as a molecular chaperone by preventing aggregation of mildly denatured proteins. Glycation, the reaction of sugars and ascorbate with proteins, causes covalent cross-linking and reduces the chaperone function of alpha-crystallin. We demonstrated that methylglyoxal (MGO), a metabolic alpha-dicarbonyl compound, modifies arginine residues in alpha-crystallin and enhances its chaperone function. We wanted to determine whether modification by MGO could protect alpha-crystallin from glycation-mediated cross-linking and loss of chaperone function. Our results show that MGO-modification of isolated bovine lens alpha-crystallin inhibits formation of pentosidine, a glycation-derived protein crosslink. Proteins in organ cultured rat lenses were similarly protected from pentosidine formation. Glycation by sugars and ascorbate resulted in almost complete loss of chaperone function of alpha-crystallin. Surprisingly, addition of MGO during or before glycation not only inhibited the loss of chaperone function, but it actually enhanced the chaperone function of alpha-crystallin. Together, these data suggest that in the aging lens, MGO inhibits glycation-mediated pentosidine synthesis and the loss of chaperone function of alpha-crystallin.
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