1jg9
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(New page: 200px<br /><applet load="1jg9" size="450" color="white" frame="true" align="right" spinBox="true" caption="1jg9, resolution 1.66Å" /> '''Crystal Structure of...)
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Revision as of 16:06, 20 November 2007
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Crystal Structure of Amylosucrase from Neisseria polysaccharea in Complex with D-glucose
Overview
The structure of amylosucrase from Neisseria polysaccharea in complex with, beta-D-glucose has been determined by X-ray crystallography at a, resolution of 1.66 A. Additionally, the structure of the inactive active, site mutant Glu328Gln in complex with sucrose has been determined to a, resolution of 2.0 A. The D-glucose complex shows two well-defined, D-glucose molecules, one that binds very strongly in the bottom of a, pocket that contains the proposed catalytic residues (at the subsite -1), in a nonstrained (4)C(1) conformation, and one that binds in the packing, interface to a symmetry-related molecule. A third weaker D-glucose-binding, site is located at the surface near the active site pocket entrance. The, orientation of the D-glucose in the active site emphasizes the Glu328 role, as the general acid/base. The binary sucrose complex shows one molecule, bound in the active site, where the glucosyl moiety is located at the, alpha-amylase -1 position and the fructosyl ring occupies subsite +1., Sucrose effectively blocks the only visible access channel to the active, site. From analysis of the complex it appears that sucrose binding is, primarily obtained through enzyme interactions with the glucosyl ring and, that an important part of the enzyme function is a precise alignment of a, lone pair of the linking O1 oxygen for hydrogen bond interaction with, Glu328. The sucrose specificity appears to be determined primarily by, residues Asp144, Asp394, Arg446, and Arg509. Both Asp394 and Arg446 are, located in an insert connecting beta-strand 7 and alpha-helix 7 that is, much longer in amylosucrase compared to other enzymes from the, alpha-amylase family (family 13 of the glycoside hydrolases).
About this Structure
1JG9 is a Single protein structure of sequence from Neisseria polysaccharea with GLC as ligand. Active as Amylosucrase, with EC number 2.4.1.4 Full crystallographic information is available from OCA.
Reference
Crystal structures of amylosucrase from Neisseria polysaccharea in complex with D-glucose and the active site mutant Glu328Gln in complex with the natural substrate sucrose., Mirza O, Skov LK, Remaud-Simeon M, Potocki de Montalk G, Albenne C, Monsan P, Gajhede M, Biochemistry. 2001 Jul 31;40(30):9032-9. PMID:11467966
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