Vitellogenin-6 Is a Major Carbonylated Protein in Aged Nematode, Caenorhabditis elegans

Recently we found that protein carbonyl content increases with age in wild-type as well as long- and short-lived Caenorhabditis elegans nematodes in inverse correlation with life span (Adachi et al., J. Gerontol. 53A, B240–B244, 1998; Yasuda et al., J. Gerontol. 54A, B47–B51, 1999). In the present study, we investigated carbonyl modification of individual proteins in young and old wild-type nematodes by two-dimensional immunoblot using antibodies against 2,4-dinitrophenylhydrazones. A protein with apparent molecular weight of 110 kDa was found to be a major carbonylated protein in aged animals. Amino acid sequence of peptide fragments of the protein was identical to that of vitellogenin-6, a yolk protein synthesized in and secreted from the intestine during egg-laying stage. Although the function(s) of the protein in aged nematodes is unclear, we suggest that the protein may have a role to protect other cellular components from oxidation because of its metal binding capacity.