FIG. 4.

Effect of temperature on PalI, PalI: E⁴⁹⁸P, and PalI: E⁴⁹⁸P/R³¹⁰P. Enzymes were analyzed for activity (A) and in a thermoinactivation assay at 50°C (B). To test for thermoinactivation, enzyme samples (500 μl, 20 μg/ml) in 0.1 M citrate-phosphate buffer (pH 6.0) were incubated at 50°C, and the aliquots (50 μl) were removed at different times and assayed at 35°C for residual activity. Residual activities are shown as the logarithms of the specific activities. Solid circles, PalI; open circles, PalI:E⁴⁹⁸P; open rhombuses, PalI:E⁴⁹⁸P/R³¹⁰P.