A specific gas chromatographic analysis for cysteinyl-S-sulfonate residues in physiologically significant proteins treated with sulfite.

It has been shown in previous studies that when sulfite is absorbed by rabbits via either inhalation of SO2 or oral exposure to sulfite, the hydrated form, bisulfite, interacts with plasma disulfides where it is suspected to be in the form, cysteine-S-sulfonate. A rapid and specific gas chromatographic analysis procedure for cysteine-S-sulfonate has been developed to better study the distribution of sulfite in biological systems. Sulfonated proteins are enzymatically hydrolyzed to ensure stability of the acid labile S-sulfonate disulfide. The hydrolysate is then applied to a 6 cm cation-exchange column and eluted with 0.1 N HCl, which elutes the acidic cysteine-S-sulfonate with the void volume of the column, leaving behind any remaining cysteine. The silylated derivatives of the column effluent are prepared using Tri-Sil/BSA. These derivatives are injected into a gas chromatograph equipped with a flame-photometric detector operating in the sulfur mode, 2% OV-101 on Chromosorb W/HP 1/4 inch glass column, oven temperature 140 degrees C, and carrier flow rate of 86 mL/min. The presence of cysteine-S-sulfonate in sulfite-treated rabbits has been directly determined by the described method.