Endo-1,6-beta-glucanase that has highest activity against the beta-1,6-glucan pustulan. Also active against the beta-1,6-glucan lutean. Lower activity against laminarin (beta-1,3-glucan with beta-1,6-branches). Little or no activity against gentiobiose, yeast glucan, lichenin, scleroglucan, curdlan, barley glucan, CM cellulose, HE cellulose, pachyman and pullulan. Random hydrolysis of (1->6)-linkages in (1->6)-beta-D-glucans. Optimum pH is 6.5 at 40 degrees Celsius. Retains at least 80% of activity after incubation for 24 hours at 4 degrees Celsius between pH 4.5 and pH 9.5. Optimum temperature is 50 degrees Celsius at pH 5.0. Stable when incubated for 30 minutes at up to 50 degrees Celsius, little activity at 75 degrees Celsius or above. Belongs to the glycosyl hydrolase 5 (cellulase A) family.