Figure 4
From: The unusual properties of lactoferrin during its nascent phase
Average pKa determination. (A) The rLF (0.6 μM) was reacted with NBD-Cl (0.1 mM) in 0.2 M urea at variable pH values, 25 °C (red line). The average pKa estimated was 4.9 ± 0.1. The error bars represent the SD from three independent experiments. As a control the pKa value of GSH (pKa = 9.0, grey line) is reported according to Ref. 9. The theoretical curve of an unperturbed protein cysteine (pKa = 9.1, black line) is also reported. (B) Dependence of the second order kinetic constants (αkRS-) on pKa for the reaction of several thiols with disulfides at pH 7.4. The pKa values of 4.9, 7.4, and 9.0 are marked with red, green, and blue dotted lines, respectively. Figure modified from Ref. 29.
