Formation of disulphide bonds in the reaction of SH group-containing amino acids with trimethylamine N-oxide. A regulatory mechanism in proteins.

Two amino acids containing SH group (cysteine and homocysteine)+trimethylamine N-oxide systems were studied by FTIR and 1H NMR spectroscopy. This study demonstrates that cysteine and homocysteine ethylesters react with trimethylamine N-oxide. Immediately after mixing, SH...ON<==>S-...H+ ON hydrogen bonds with large proton polarizability are are formed. Then a reaction proceeds resulting in the formation of corresponding disulphides. Trimethylamine N-oxide is present in biological systems. Thus, our results suggest that trimethylamine N-oxide may play a regulatory role in S-S bond formation in enzymes and other proteins.