Figure 4.

Effect of pH at physiological concentrations of CO₂ on the PN-dependent formation of carbonyls in GS and BSA. Reaction mixtures (1.0 ml) contained 1.0 mg GS (open circles) or 1.0 mg BSA (closed circles) and amounts of KHCO₃ (15–700 mM) as needed to obtain the indicated pH values in the presence of 1.3 mM CO₂. After purging for 30 min with a 5% CO₂/95% N₂ gas mixture, 3.0 mM PN was added, the samples were incubated at room temperature for 5 min and then was assayed for carbonyl content as described in Materials and Methods.