1Department of Biotechnology, Indian Institute of Technology Guwahati, North Guwahati, 781 039, Assam.
2CIISA-Faculdade de Medicina Veterinária, Rua Prof. Cid dos Santos, 1300 477, Lisbon, Portugal.
*E-mail: arungoyl@iitg.ernet.in, Tel: 91 361 2582208 Fax: 91 361 2582249.
A family 26, glycoside hydrolase (GH26) of bi-functional cellulase (GH26-GH5) with two catalytic modules GH26 and GH5 having different catalytic activities from Clostridium thermocellum was amplified through PCR and cloned into an expression vector pET21a. The 30 kDa protein was hyper-expressed in BL-21 E. coli cells and was purified to homogeneity by a single step purification method using immobilised metal ion affinity-chromatography. The purified clostridial GH26 enzyme, unlike other members of the family GH26, which normally display activity towards manno - configured substrates like mannan, galactomannan or glucomannan showed no activity towards these substrates. However, the clostridial GH26 enzyme showed high activity towards gluco configured substrates such as lichenan and glucan. The clostridial GH26 is highly specific endo acting-1,3–1,4-glucanase. The clostridial enzyme GH26 is maximally active within pH range, 6–8.5 and has a wider optimum temperature range, 60–80°C.
Glycoside hydrolase, Clostridium thermocellum, cellulase, E. coli, PCR
