FIG. 4.

Thermostability of PGI purified from P. furiosus enzyme (1.8 μg) was incubated in 50 μl of 50 mM potassium phosphate buffer, pH 7.0, at 70°C (□), 80°C (▵), 90°C (●), and 100°C (○). At the times indicated, 15-μl aliquots were withdrawn and assayed for remaining activity at 55°C in the direction of glucose-6-phosphate formation. One hundred percent activity corresponded to the specific activity of PGI of 30 U/mg.