Figure 3.
Estimates of LQQC*PFEDHVK adducts recovered from trypsin/chymotrypsin digestion of m-CPBA-oxidized or nonoxidized HONH-PhIP-modified SA, without or with denaturation. Adduct formation was estimated by UPLC-ESI/MS2, employing LQQC*PF (C-[SO2]-[2H5]-PhIP) sulfonamide and LQQC*PF (C-[S=O]-[2H5]-PhIP) sulfinamide as internal standards. The ionization efficiencies of the mixed cleavage peptide adducts LQQC*PFEDHVK were assumed to be comparable to the ionization efficiencies of the internal standards of [2H5]-PhIP-modified LQQC*PF. Total PhIP bound to SA was determined by UV measurement at 320 nm.14