A Neutral Thermostable ?-1,4-Glucanase from Humicola insolens Y1 with Potential for Applications in Various Industries.

ABSTRACT: We cloned a new glycoside hydrolase family 6 gene, Hicel6C, from the thermophilic fungus Humicola insolens Y1 and expressed it in Pichia pastoris. Using barley ?-glucan as a substrate, recombinant HiCel6C protein exhibited neutral pH (6.5) and high temperature (70°C) optima. Distinct from most reported acidic fungal endo-?-1,4-glucanases, HiCel6C was alkali-tolerant, retaining greater than 98.0, 61.2, and 27.6% of peak activity at pH 8.0, 9.0, and 10.0, respectively, and exhibited good stability over a wide pH range (pH 5.0-11.0) and at temperatures up to 60°C. The Km and Vmax values of HiCel6C for barley ?-glucan were 1.29 mg/mL and 752 ?mol/min·mg, respectively. HiCel6C was strictly specific for the ?-1,4-glucoside linkage exhibiting activity toward barley ?-glucan, lichenan, and carboxy methylcellulose sodium salt (CMC-Na), but not toward laminarin (1,3-?-glucan). HiCel6C cleaved the internal glycosidic linkages of cellooligosaccharides randomly and thus represents an endo-cleaving enzyme. The predominant product of polysaccharide hydrolysis by HiCel6C was cellobiose, suggesting that it functions by an endo-processive mechanism. The favorable properties of HiCel6C make it a good candidate for basic research and for applications in the textile and brewing industries.

SUBMITTER: Xu X 

PROVIDER: S-EPMC4409357 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature