Figure 4. SSO1949 hydrolyses a fluorescent cellohexaoside.

Fluorescent hexaoside (3 μM) [18] was incubated with 0.1 μM SSO1949 in 100 mM potassium phosphate (pH 1.8) at 75 °C. Excitation was at 340 nm and fluorescence increase due to the hydrolysis of the hexaoside was monitored at 470 nm. The fluorescence intensity was sampled every 30 s. Shown are a progress curve with enzyme (—) and a control reaction without enzyme (---). Spontaneous degradation of the substrate even at these extreme assay conditions is very low, with a half-life of several hours.