1tml
From Proteopedia
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CRYSTAL STRUCTURE OF THE CATALYTIC DOMAIN OF A THERMOPHILIC ENDOCELLULASE
Overview
One way to improve the economic feasibility of biomass conversion is to, enhance the catalytic efficiency of cellulases through protein, engineering. This requires that high-resolution structures of cellulases, be available. Here we present the structure of E2cd, the catalytic domain, of the thermophilic endocellulase E2 from Thermomonospora fusca, as, determined by X-ray crystallography. The structure was solved by multiple, isomorphous replacement at 2.6-A resolution and has been refined at 1.8-A, resolution to an R-value of 18.4% for all reflections between 10- and, 1.8-A resolution. The fold of E2cd is based on an unusual parallel, beta-barrel and is equivalent to the fold determined for the catalytic, domain of cellobiohydrolase II, an exocellulase from Trichoderma reesei, [Rouvinen et al. (1990) Science 249, 380-385]. The active site cleft of, the enzyme, approximately 11 A deep and running the entire length of the, molecule, is seen to be completely free for ligand binding in the crystal., A 2.2-A resolution analysis of crystals of E2cd complexed with cellobiose, an inhibitor, shows how cellobiose binds in the active site and interacts, with several residues which line the cleft. Catalytic roles are suggested, for three aspartic acid residues at the active site. A comparison of the, E2cd and CBHIIcd structures reveals a large difference in their active, site accessibilities and supports the hypothesis that the main difference, between endo- and exocellulases is the degree to which their active sites, are accessible to substrate.
About this Structure
1TML is a Single protein structure of sequence from Thermobifida fusca with SO4 as ligand. Active as Cellulase, with EC number 3.2.1.4 Full crystallographic information is available from OCA.
Reference
Crystal structure of the catalytic domain of a thermophilic endocellulase., Spezio M, Wilson DB, Karplus PA, Biochemistry. 1993 Sep 28;32(38):9906-16. PMID:8399160
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