1BVW
CELLOBIOHYDROLASE II (CEL6A) FROM HUMICOLA INSOLENS
Summary for 1BVW
| Entry DOI | 10.2210/pdb1bvw/pdb |
| Descriptor | PROTEIN (CELLOBIOHYDROLASE II), alpha-D-mannopyranose, 2-acetamido-2-deoxy-beta-D-glucopyranose, ... (6 entities in total) |
| Functional Keywords | cellulose degradation, cellobiohydrolase, cellulase, glycoside hydrolase family 6, hydrolase |
| Biological source | Humicola insolens |
| Total number of polymer chains | 1 |
| Total formula weight | 40435.15 |
| Authors | Varrot, A.,Davies, G.J.,Schulein, M. (deposition date: 1998-09-19, release date: 1999-09-18, Last modification date: 2024-10-30) |
| Primary citation | Varrot, A.,Hastrup, S.,Schulein, M.,Davies, G.J. Crystal structure of the catalytic core domain of the family 6 cellobiohydrolase II, Cel6A, from Humicola insolens, at 1.92 A resolution. Biochem.J., 337:297-304, 1999 Cited by PubMed Abstract: The three-dimensional structure of the catalytic core of the family 6 cellobiohydrolase II, Cel6A (CBH II), from Humicola insolens has been determined by X-ray crystallography at a resolution of 1.92 A. The structure was solved by molecular replacement using the homologous Trichoderma reesei CBH II as a search model. The H. insolens enzyme displays a high degree of structural similarity with its T. reesei equivalent. The structure features both O- (alpha-linked mannose) and N-linked glycosylation and a hexa-co-ordinate Mg2+ ion. The active-site residues are located within the enclosed tunnel that is typical for cellobiohydrolase enzymes and which may permit a processive hydrolysis of the cellulose substrate. The close structural similarity between the two enzymes implies that kinetics and chain-end specificity experiments performed on the H. insolens enzyme are likely to be applicable to the homologous T. reesei enzyme. These cast doubt on the description of cellobiohydrolases as exo-enzymes since they demonstrated that Cel6A (CBH II) shows no requirement for non-reducing chain-ends, as had been presumed. There is no crystallographic evidence in the present structure to support a mechanism involving loop opening, yet preliminary modelling experiments suggest that the active-site tunnel of Cel6A (CBH II) is too narrow to permit entry of a fluorescenyl-derivatized substrate, known to be a viable substrate for this enzyme. PubMed: 9882628DOI: 10.1042/0264-6021:3370297 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.92 Å) |
Structure validation
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