Electrophiles activate hTRPA1 faster than they react with conventional sulfhydryl groups in vitro. (A) 50 µM cinnamaldehyde activation of hTRPA1 in HEK293 (top, n = 28) and 50 µM cinnamaldehyde reaction with 5 mM GSH (bottom, n = 3). (B) 200 µM IA activation of hTRPA1 in HEK293 (top, n = 96) and its reaction with 5 mM GSH (bottom, n = 3). (A and B) Error bars denote SEM. (C) Absorbance of TNB at 412 nm. (D) Mean ± SEM loss of 100 µM TNB absorption at 412 nm after sequential reaction with 30 µM IA, 1 mM IA, and 100 mM NMM in control conditions (n = 3) and in the presence of 5 mM GSH (n = 3). (E) Mean ± SEM TNB loss after reaction with 30 µM IA, 1 mM NEM, and 100 mM NMM in control (n = 3) and with 5 mM GSH (n = 3). Error bars are too small to see on this scale.