3tf4
ENDO/EXOCELLULASE:CELLOTRIOSE FROM THERMOMONOSPORA
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OverviewOverview
Cellulase E4 from Thermomonospora fusca is unusual in that it has, characteristics of both exo- and endo-cellulases. Here we report the, crystal structure of a 68K M(r) fragment of E4 (E4-68) at 1.9 A, resolution. E4-68 contains both a family 9 catalytic domain, exhibiting an, (alpha/alpha)6 barrel fold, and a family III cellulose binding domain, having an antiparallel beta-sandwich fold. While neither of these folds is, novel, E4-68 provides the first cellulase structure having interacting, catalytic and cellulose binding domains. The complexes of E4-68 with, cellopentaose, cellotriose and cellobiose reveal conformational changes, associated with ligand binding and allow us to propose a catalytic, mechanism for family 9 enzymes. We also provide evidence that E4 has two, novel characteristics: first it combines exo- and endo-activities and, second, when it functions as an exo-cellulase, it cleaves off, cellotetraose units.
About this StructureAbout this Structure
3TF4 is a Single protein structure of sequence from Thermobifida fusca with and as ligands. Active as Cellulase, with EC number 3.2.1.4 Known structural/functional Sites: , , , , and . Full crystallographic information is available from OCA.
ReferenceReference
Structure and mechanism of endo/exocellulase E4 from Thermomonospora fusca., Sakon J, Irwin D, Wilson DB, Karplus PA, Nat Struct Biol. 1997 Oct;4(10):810-8. PMID:9334746
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