Identification of Rosmarinic Acid-Adducted Sites in Meat Proteins in a Gel Model under Oxidative Stress by Triple TOF MS/MS.

Triple TOF MS/MS was used to identify adducts between rosmarinic acid (RosA)-derived quinones and meat proteins in a gel model under oxidative stress. Seventy-five RosA-modified peptides responded to 67 proteins with adduction of RosA. RosA conjugated with different amino acids in proteins, and His, Arg, and Lys adducts with RosA were identified for the first time in meat. A total of 8 peptides containing Cys, 14 peptides containing His, 48 peptides containing Arg, 64 peptides containing Lys, and 5 peptides containing N-termini that which participated in adduction reaction with RosA were identified, respectively. Seventy-seven adduction sites were subdivided into all adducted proteins including 2 N-terminal adduction sites, 3 Cys adduction sites, 4 His adduction sites, 29 Arg adduction sites, and 39 Lys adduction sites. Site occupancy analyses showed that approximately 80.597% of the proteins carried a single RosA-modified site, 14.925% retained two sites, 1.492% contained three sites, and the rest 2.985% had four or more sites. Large-scale triple TOF MS/MS mapping of RosA-adducted sites reveals the adduction regulations of quinone and different amino acids as well as the adduction ratios, which clarify phenol-protein adductions and pave the way for industrial meat processing and preservation.