Fig. 2.

Titrations for quercetinase activities of the pirin-like protein from P. stutzeri Zobell as a function of increasing concentrations of added Cu²⁺ (Fig. 2A) and Fe²⁺ (Fig. 2B) ions. Conditions: protein concentration, 4 μM, in 10 mM potassium phosphate buffer (pH 6.0) supplemented with 0.1 M NaCl.