Trichoderma longibrachiatum, when cultivated on untreated ground mushroom (Agaricus bisporus) fruiting bodies as the only carbon substrate, exhibited extracellular laminarinase (endo-1,3(4)-ß-glucanase EC 188.8.131.52) activity. The general physicochemical and catalytic properties of that enzyme preparation were examined. The apparent Kmand Vmaxvalues were determined to be 137 mg ml-1) and 0.62 nmol s-1, respectively. The optimum pH and temperature for enzyme activity were 5.0 and 50°C, and among several buffers tested at pH 5.0, sodium acetate was found to be optimum. The energy of activation, Ea, and temperature coefficient, Q10(between 30 and 40°C), were calculated to be 3.7 kcal mol-1and 1.02, respectively. The enzyme was stable between pH 3.0 and 9.0 when stored at 4°C for 48 h. In the absence of substrate, enzyme activity was unaffected at 30°C for 1 h but lost complete activity within 10 min at 60°C. Among a number of metal ions and enzyme inhibitors tested, only Mn2+, Hg2+, N-bromosuccinimideand potassium permanganate showed prominent inhibition. © 1987.
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