Table 3 Reactivity of cysteines of fully reduced SsPDO toward thiol reagents, pH 7.4.

From: Ultra-rapid glutathionylation of chymotrypsinogen in its molten globule-like conformation: A comparison to archaeal proteins

Reagents

Free Cysteine

Free GSH

Reduced SsPDO

k (M−1 s−1)

k (M−1 s−1)

k (M−1 s−1) (-SH/mole SsPDO)

E.R.

GSSG

0.7a

(0.2)b

—

6 ± 1 (2)

8.57

30

Cystine

—

12

10 ± 2 (2)

0.83

Cystamine

—

55

20 ± 2 (2)

0.36

Homocystine

—

0.6

6 ± 1 (2)

10

DTNBc

—

20

1900 ± 110 (3)

95

CDNB

—

0.07

1.6 ± 0.1 (3)

23

NBD-Cl

—

8

72 ± 3 (2)

9

  1. aExperimental value for free cys (pKa = 8.55);
  2. bTheoretical value for unperturbed protein cysteine (pKa = 9.1);
  3. cpH 5.0;
  4. E.R., Enhanced reactivity;
  5. Data are Mean ± S.D.
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