2d43
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(New page: 200px<br /><applet load="2d43" size="450" color="white" frame="true" align="right" spinBox="true" caption="2d43, resolution 2.80Å" /> '''Crystal structure of...)
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Revision as of 07:18, 21 November 2007
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Crystal structure of arabinofuranosidase complexed with arabinotriose
Overview
Alpha-L-arabinofuranosidase catalyses the hydrolysis of the alpha-1,2-, alpha-1,3-, and alpha-1,5-L-arabinofuranosidic bonds in, L-arabinose-containing hemicelluloses such as arabinoxylan. AkAbf54 (the, glycoside hydrolase family 54 alpha-L-arabinofuranosidase from Aspergillus, kawachii) consists of two domains, a catalytic and an arabinose-binding, domain. The latter has been named AkCBM42 [family 42 CBM, (carbohydrate-binding module) of AkAbf54] because homologous domains are, classified into CBM family 42. In the complex between AkAbf54 and, arabinofuranosyl-alpha-1,2-xylobiose, the arabinose moiety occupies the, binding pocket of AkCBM42, whereas the xylobiose moiety is exposed to the, solvent. AkCBM42 was found to facilitate the hydrolysis of insoluble, arabinoxylan, because mutants at the arabinose binding site exhibited, markedly decreased activity. The results of binding assays and affinity, gel electrophoresis showed that AkCBM42 interacts with, arabinose-substituted, but not with unsubstituted, hemicelluloses., Isothermal titration calorimetry and frontal affinity chromatography, analyses showed that the association constant of AkCBM42 with the, arabinose moiety is approximately 10(3) M(-1). These results indicate that, AkCBM42 binds the non-reducing-end arabinofuranosidic moiety of, hemicellulose. To our knowledge, this is the first example of a CBM that, can specifically recognize the side-chain monosaccharides of branched, hemicelluloses.
About this Structure
2D43 is a Single protein structure of sequence from Aspergillus kawachii. Active as Alpha-N-arabinofuranosidase, with EC number 3.2.1.55 Full crystallographic information is available from OCA.
Reference
The family 42 carbohydrate-binding module of family 54 alpha-L-arabinofuranosidase specifically binds the arabinofuranose side chain of hemicellulose., Miyanaga A, Koseki T, Miwa Y, Mese Y, Nakamura S, Kuno A, Hirabayashi J, Matsuzawa H, Wakagi T, Shoun H, Fushinobu S, Biochem J. 2006 Nov 1;399(3):503-11. PMID:16846393
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