Liu Guodong, Wei Xiaomin, Qin Yuqi, Qu Yinbo
State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong, P.R. China.
J Gen Appl Microbiol. 2010 Jun;56(3):223-9. doi: 10.2323/jgam.56.223.
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 recombinant enzyme showed a higher activity on konjac glucomannan (KGM) than on sodium carboxymethyl cellulose (CMC-Na) or phosphoric acid swollen cellulose (PASC). The highest hydrolytic activity was detected at pH5.0 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 degrees C and about 90% relative activities were retained at 70 degrees C. Products released 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.
从斜卧青霉114 - 2中克隆了编码糖苷水解酶（GH）家族45内切葡聚糖酶（Cel45A）的基因，并在毕赤酵母中表达。据我们所知，这是首次对青霉属物种中GH家族45蛋白进行表征的报道。纯化后的重组酶对魔芋葡甘露聚糖（KGM）的活性高于对羧甲基纤维素钠（CMC - Na）或磷酸膨胀纤维素（PASC）的活性。在pH5.0时对KGM检测到最高水解活性，在pH3.5时对CMC - Na检测到最高水解活性，这表明Cel45A对两种底物的作用模式可能不同。两种底物的最适温度均为60℃，在70℃时保留约90%的相对活性。从PASC和CMC - Na释放的产物主要是纤维二糖、纤维三糖和纤维四糖。具有较高葡甘露聚糖酶活性的蛋白质可能有助于斜卧青霉在自然状态下对木质纤维素的有效降解。
