uncategorized crosslinked residues modified residue that can arise from different natural residues L-cysteinyl-L-selenocysteine 251.1699981689453125 251.947174072265625 A protein modification that forms L-cysteinyl-L-selenocysteine either by the natural process of cross-linking an L-cysteine residue and an L-selenocysteine residue, or by the hypothetical process of substituting a selenium for a sulfur atom in cystine. C 6 H 8 N 2 O 2 S 1 Se 1 C, X Cross-link 2. MOD:01627 PSI-MOD natural crosslinked L-cysteine residue