The species-specific chemical shifts together with the thiolate-specific protonation shifts determined for the additional compounds studied (beyond cysteine and cystine) bearing thiol moiety.

The uncertainty of determination for chemical shift on the ppm scale is 0.001 and 0.01 for 1H and 13C chemical shift values, respectively. Mean value and standard deviation of the protonation shifts (Δδ) are: 0.14±0.07, 0.08±0.05, -1.62±0.28, 0.37±0.05, -2.64±0.30 for the nuclei found in the table, respectively.