Differential reactivity of the functional sulfhydryl groups of cysteine-32 and cysteine-35 present in the reduced form of thioredoxin from Escherichia coli.

@article{Kallis1980DifferentialRO,
  title={Differential reactivity of the functional sulfhydryl groups of cysteine-32 and cysteine-35 present in the reduced form of thioredoxin from Escherichia coli.},
  author={G B Kallis and Arne Holmgren},
  journal={The Journal of biological chemistry},
  year={1980},
  volume={255 21},
  pages={10261-5}
}
Only one of the sulfhydryl groups from Cys-32 and Cys-35 in the active center of native Escherichia coli thioredoxin-(SH)2 was alkylated by excess iodoacetic acid at pH values below 8.0. Both groups reacted in the protein denatured with 4.5 M guanidine hydrochloride. The second order rate of alkylation of thioredoxin-(SH)2 with 1 eq of iodoacetic acid was pH-dependent and showed independent initial reactions of one thiolate ion with a pK value of 6.7 and a second with a pK value close to 9.0… CONTINUE READING