2guy: Difference between revisions

Revision as of 05:34, 4 May 2008

Orthorhombic crystal structure (space group P21212) of Aspergillus niger alpha-amylase at 1.6 A resolution

OverviewOverview

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 StructureAbout this Structure

2GUY is a Single protein structure of sequence from Aspergillus oryzae. Full crystallographic information is available from OCA.

ReferenceReference

Monoclinic crystal form of Aspergillus niger alpha-amylase in complex with maltose at 1.8 angstroms resolution., Vujicic-Zagar A, Dijkstra BW, Acta Crystallogr Sect F Struct Biol Cryst Commun. 2006 Aug 1;62(Pt, 8):716-21. Epub 2006 Jul 24. PMID:16880540 Page seeded by OCA on Sun May 4 05:34:08 2008

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OCA

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 '''Orthorhombic crystal structure (space group P21212) of Aspergillus niger alpha-amylase at 1.6 A resolution'''
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 [[Category: Single protein]]
 [[Category: Zagar, A Vujicic.]]
-[[Category: (beta-alpha) 8 barrel]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May  4 05:34:08 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 03:21:59 2008''