Figure 1.

PG2 hydrolysis of PGA in response to pH. Reaction mixtures contained 0.5 mL of PGA (4 mg mL⁻¹) in 20 mm NaOAc and 150 mm NaCl or 20 mm KOAc and 100 mm KCl, adjusted to the desired pH with dilute HCl or NaOH. After the addition of 50 μL of purified PG2 (approximately 2 μg of protein), the samples were incubated for 1 h at 34°C. Activity was measured reductometrically using galacturonic acid as the standard. •, 150 mm NaCl; ○, 100 mm KCl.