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From Proteopedia
The importance of the Abn2 calcium cluster in the endo-1,5- arabinanase activity from Bacillus subtilis
Structural highlights
FunctionEABN2_BACSU Involved in the degradation of arabinan and is a key enzyme in the complete degradation of the plant cell wall. Catalyzes the internal cleavage of alpha-(1->5)-L-arabinofuranosyl residues of the alpha-1,5-L-arabinan to produce arabino-oligosaccharides and L-arabinose. It is also active toward linear branched sugar beet arabinan, and pectin from apple.[1] [2] Publication Abstract from PubMedArabinanase is a glycosyl hydrolase that is able to cleave the glycosidic bonds of alpha-1,5-L-arabinan, releasing arabino-oligosaccharides and L-arabinose. The enzyme has two domains, an N-terminal catalytic domain with a characteristic beta-propeller fold and a C-terminal domain whose function is unknown. A calcium ion, located near the catalytic site, serves to stabilize the N-terminal domain, but it has also been proposed to play a key role in the enzyme mechanism. The present work describes the structure of an inactive mutant of the wild-type enzyme (H318Q) and in which the calcium ion has been adventitiously replaced by nickel. These structural studies, together with functional and modelling studies, clearly support the role of the calcium ion in the overall reaction mechanism. The importance of the Abn2 calcium cluster in the endo-1,5-arabinanase activity from Bacillus subtilis.,McVey CE, Ferreira MJ, Correia B, Lahiri S, de Sanctis D, Carrondo MA, Lindley PF, de Sa Nogueira I, Soares CM, Bento I J Biol Inorg Chem. 2014 Feb 19. PMID:24549757[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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