2guy
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(New page: 200px<br /><applet load="2guy" size="450" color="white" frame="true" align="right" spinBox="true" caption="2guy, resolution 1.59Å" /> '''Orthorhombic crystal...)
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Revision as of 09:16, 21 November 2007
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Orthorhombic crystal structure (space group P21212) of Aspergillus niger alpha-amylase at 1.6 A resolution
Overview
Aspergillus niger alpha-amylase catalyses the hydrolysis of, alpha-1,4-glucosidic bonds in starch. It shows 100% sequence identity to, the A. oryzae homologue (also called TAKA-amylase), three crystal, structures of which have been published to date. Two of them belong to the, orthorhombic space group P2(1)2(1)2(1) with one molecule per asymmetric, unit and one belongs to the monoclinic space group P2(1) with three, molecules per asymmetric unit. Here, the purification, crystallization and, structure determination of A. niger alpha-amylase crystallized in the, monoclinic space group P2(1) with two molecules per asymmetric unit in, complex with maltose at 1.8 angstroms resolution is reported. Furthermore, a novel 1.6 angstroms resolution orthorhombic crystal form (space group, P2(1)2(1)2) of the native enzyme is presented. Four maltose molecules are, observed in the maltose-alpha-amylase complex. Three of these occupy, active-site subsites -2 and -1, +1 and +2 and the hitherto unobserved, subsites +4 (Asp233, Gly234) and +5 (Asp235). The fourth maltose molecule, binds at the distant binding sites d1 (Tyr382) and d2 (Trp385), also, previously unobserved. Furthermore, it is shown that the active-site, groove permits different binding modes of sugar units at subsites +1 and, +2. This flexibility of the active-site cleft close to the catalytic, centre might be needed for a productive binding of substrate chains and/or, release of products.
About this Structure
2GUY is a Single protein structure of sequence from Aspergillus oryzae with CA as ligand. Active as Alpha-amylase, with EC number 3.2.1.1 Full crystallographic information is available from OCA.
Reference
Monoclinic crystal form of Aspergillus niger alpha-amylase in complex with maltose at 1.8 angstroms resolution., Vujicic-Zagar A, Dijkstra BW, Acta Crystallograph Sect F Struct Biol Cryst Commun. 2006 Aug 1;62(Pt, 8):716-21. Epub 2006 Jul 24. PMID:16880540
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