A novel thermostable and halotolerant xylanase from Colletotrichum graminicola

Publication date: Available online 8 May 2017 Source:Journal of Molecular Catalysis B: Enzymatic Author(s): Sibeli Carli, Luana Parras Meleiro, Jose Cesar Rosa, Luiz Alberto Beraldo Moraes, João Atílio Jorge, Douglas Chodi Masui, Rosa P.M. Furriel A novel endoxylanase from Colletotrichum graminicola (Excg1) was purified. Similar apparent molecular masses were estimated by gel filtration (17.3±1.9kDa) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (20.0±2.4kDa), suggesting that Excg1 is monomeric. The enzyme showed good halotolerance, retaining about 85% and 50% of the control activity in the presence of 0.5molL−1 and 3.0molL−1 NaCl, respectively. The optimum temperature of Excg1 (65°C) was not affected by NaCl, but the optimum pH rose from 5.5 in the absence and presence of 0.5molL−1 NaCl to 6.0, in 2.5molL−1 NaCl. Excg1 was highly thermostable at 50°C, with half-lives around 48h in either water or 0.5molL−1 NaCl and a residual activity of 75% at 2.5molL−1 NaCl. Excg1 was fully stable at pH 3.0 to 10.0 in the absence of salt, and from pH 4.0 to 10.0 in the presence of 0.5molL−1 and 2.5molL−1 NaCl. The enzyme hydrolyzed beechwood xylan with maximal velocity and apparent affinity constant of 481.3±34.0Umg−1 and 3.7±0.3mgmL−1, respectively. Similar kinetic parameters were obtained in the presence of 0.5molL−1 NaCl, but a maximum velocity about 34% lower was determined in 2.5molL−1 NaCl. Excg1 was tolerant to various organic...

Source: Journal of Molecular Catalysis B: Enzymatic - May 9, 2017 Category: Biochemistry Source Type: research