Characterization of the endoglucanase and glucomannanase activities of a glycoside hydrolase family 45 protein from Penicillium decumbens 114-2

Abstract

The gene encoding a glycoside hydrolase (GH) family 45 endoglucanase (Cel45A) was cloned from P. decumbens 114-2 and expressed in Pichia pastoris. To our knowledge, this is the first report of characterization of a GH family 45 protein from Penicillium species. The purified recom-binant enzyme showed a higher activity on konjac glucomannan (KGM) than on sodium car-boxymethyl cellulose (CMC-Na) or phosphoric acid swollen cellulose (PASC). The highest hydrolytic activity was detected at pH 5.0 on KGM and pH 3.5 on CMC-Na, indicating the mode of action on the two substrates may be different for Cel45A. The optimum temperatures on the two substrates were both 60°C and about 90% relative activities were retained at 70°C. Products re-leased from PASC and CMC-Na were mainly cellobiose, cellotriose and cellotetraose. The protein with higher glucomannanase activity might help the efficient degradation of lignocellulose by P. decumbens in the natural state.