Figure 7.

Reactivity of Trpase-doped silica gels and Trpase in solution with L-serine. Absorption spectra of Trpase-doped gels were recorded in a solution containing 50 mM potassium phosphate (pH 7.5) at 25°C, (A) in the absence (solid line) and presence of 0.5 M L-serine after 120 min of reaction (dashed line), and after subtraction of pyruvate absorbance (dotted line), (B) in the absence (solid line) and presence of 0.5 M L-serine and 5 mM benzimidazole, after 120 min of reaction (dashed line), and after subtraction of pyruvate absorbance (dotted line). Pyruvate concentration was evaluated by a coupled lactate dehydrogenase assay (see Materials and Methods). (Inset) Absorbance changes at 423 nm (▪) and 340 nm (•) as a function of time. (C) Absorption spectra of Trpase in a solution containing 50 mM potassium phosphate (pH 7.5) at 25°C in the absence (solid line) and presence of 0.5 M L-serine (dashed line) and 0.5 M L-serine and 5 mM benzimidazole (dashed/dotted line). Spectra were corrected for the contribution of pyruvate absorption.