2bvw
From Proteopedia
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CELLOBIOHYDROLASE II (CEL6A) FROM HUMICOLA INSOLENS IN COMPLEX WITH GLUCOSE AND CELLOTETRAOSE
Overview
The mechanisms of crystalline cellulose degradation by cellulases are of, paramount importance for the exploitation of these enzymes in applied, processes, such as biomass conversion. Cellulases have traditionally been, classified into cellobiohydrolases, which are effective in the degradation, of crystalline materials, and endoglucanases, which appear to act on, "soluble" regions of the substrate. Humicola insolensCel6A (CBH II) is a, cellobiohydrolase from glycoside hydrolase family 6 whose native structure, has been determined at 1.9 A resolution [Varrot, A., Hastrup, S., Schulein, M., and Davies, G. J. (1999) Biochem. J. 337, 297-304]. Here we, present the structure of the catalytic core domain of Humicola insolens, cellobiohydrolase II Cel6A in complex with glucose/cellotetraose at 1.7 A, resolution. Crystals of Cel6A, grown in the presence of cellobiose, reveal, six binding subsites, with a single glucose moiety bound in the -2 subsite, and cellotetraose in the +1 to +4 subsites. The complex structure is, strongly supportive of the assignment of Asp 226 as the catalytic acid and, consistent with proposals that Asp 405 acts as the catalytic base. The, structure undergoes several conformational changes upon substrate binding, the most significant of which is a closing of the two active site loops, (residues 174-196 and 397-435) with main-chain movements of up to 4.5 A, observed. This complex not only defines the polysaccharide-enzyme, interactions but also provides the first three-dimensional demonstration, of conformational change in this class of enzymes.
About this Structure
2BVW is a Single protein structure of sequence from Humicola insolens with NAG, GLC, CTT, CT3 and GOL as ligands. Active as Cellulose 1,4-beta-cellobiosidase, with EC number 3.2.1.91 Full crystallographic information is available from OCA.
Reference
Structural changes of the active site tunnel of Humicola insolens cellobiohydrolase, Cel6A, upon oligosaccharide binding., Varrot A, Schulein M, Davies GJ, Biochemistry. 1999 Jul 13;38(28):8884-91. PMID:10413461
Page seeded by OCA on Wed Nov 21 08:56:26 2007
