PRODUCTION OF THE THIYL FREE RADICAL BY THE REACTION OF N-METHYL-N'-NITRO-N-NITROSOGUANIDINE WITH L-CYSTEINE

: The thiyl free radical is formed in the L-cysteine/N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) system (pH 7.8) without exposure to light as detected by the ESR spin trapping technique. The formation of N-methyl-N'-nitroguanidine in the system is identified by thin-layer chromatography. The hypothesis that the thiyl radical is formed by the attack of the nucleophilic reagent L-cysteine on the nitroso group of MNNG is verified by these results.