LAUSR

We first showed the formation of a ditryptophan (Trp-Trp) cross-link through recombination of human superoxide dismutase-tryptophanyl radicals in 2010. This and related publications received limited attention up to very recently, when similar cross-links have been reported by other investigators in different proteins. Since Trp-Trp cross-links may play a role in protein aggregation processes, they deserve further studies. Here, we report the presence of Trp-Trp cross-links (f3B2-Trp151-Trp151-f3B2 and f3B2-Trp82-Trp85) in beta crystallin irradiated in a solar simulator (SOL-UV-2) for 2–8 hours. Moreover, Trp-Trp cross-links (f3B2-Trp151-Trp151-f3B2; f3B1-Trp217-Trp220 and f3B1-Trp124-Trp127) were detectable in human lenses with advanced cataract (LOCS II). In both cases, monomer and dimers of the proteins constituting the samples were separated by SDS-PAGE and the tryptic peptides analyzed by Orbitrap Lumos Fusion. To the best of our knowledge, this is the first direct evidence for the formation of Trp-Trp cross-links in vivo.