FIG. 3.

(A) Thermostability of MTFK. The PPIase assay was used as the indicator of the thermostability of MTFK. The purified MTFK was incubated at the indicated temperature. The PPIase activity was then assayed after a 15-min incubation at 50°C. The PPIase activity was expressed as a percentage of the original activity before heat treatment and is plotted on a semilogarithmic scale. (B) The first-order rate constants of pNA release in the presence and absence of MTFK were determined by the chymotrypsin-coupled method (see Materials and Methods) at the indicated temperatures. The reactions were monitored for 250 s (15 and 20°C), 200 s (25°C), 100 s (30°C), and 50 s (35°C). ○, absence of MTFK; •, presence of MTFK.