A study of the competitive nitrosations of pyrrolidine,ascorbic acid,cysteine and p-cresol in a protein-based model system

The effects of competitive C- and S-nitrosations on the formation of nitrosopyrrolidine were studied in a protein-based model system. The results obtained were compared with those of the analogous reactions performed in solution. The competitive nitrosations were studied at pH 5-25 and 37°C and the results obtained were found to be similar in both systems: ascorbic acid, cysteine and p-cresol each reduced the formation of nitrosopyrrolidine, in decreasing amounts, by competing with pyrrolidine for the available nitrite. A second pathway of nitrosopyrrolidine formation was found which may have involved transnitrosation by the protein-bound nitrite.