Masses of trypsin digest fragments of OhrR under oxidizing and reducing conditions

  • a Z is free Cys modified with 4-vinylpyridine.

  • b The location of the disulfide bond is deduced from the modification experiment with 2-bromoethylamine and NEM (see text).

  • c C* is the S-2-aminoethylcysteine generated after treatment with 2-bromoethylamine; this residue is now a recognition site for trypsin that was cleaved on the C-terminal side of C*, proving the location of the disulfide bond between C22 and C127.