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Publication Abstract from PubMed

Tm_Cel5A, which belongs to family 5 of the glycoside hydrolases, is an extremely stable enzyme among the endo-acting glycosidases present in the hyperthermophilic organism Thermotoga maritima. Members of GH5 family shows a common (beta/alpha)(8) TIM-barrel fold in which the catalytic acid/base and nucleophile are located on strands beta-4 and beta-7 of the barrel fold. Thermally resistant cellulases are desirable for lignocellulosic biofuels production and the Tm_Cel5A is an excellent candidate for use in the degradation of polysaccharides present on biomass. This paper describes two Tm_Cel5A structures (crystal forms I and II) solved at 2.20 and 1.85A resolution, respectively. Our analyses of the Tm_Cel5A structure and comparison to a mesophilic GH5 provides a basis for the thermostability associated with Tm_Cel5A. Furthermore, both crystal forms of Tm_Cel5A possess a cadmium (Cd(2+)) ion bound between the two catalytic residues. Activity assays of Tm_Cel5A confirmed a strong inhibition effect in the presence of Cd(2+) metal ions demonstrating competition with the natural substrate for the active site. Based on the structural information we have obtained for Tm_Cel5A, protein bioengineering can be used to potentially increase the thermostability of mesophilic cellulase enzymes.

Biochemical characterization and crystal structure of endoglucanase Cel5A from the hyperthermophilic Thermotoga maritima.,Pereira JH, Chen Z, McAndrew RP, Sapra R, Chhabra SR, Sale KL, Simmons BA, Adams PD J Struct Biol. 2010 Jul 3. PMID:20599513^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.