1e1e: Difference between revisions
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==Overview== | ==Overview== | ||
The maize beta-glucosidase isoenzymes ZMGlu1 and ZMGlu2 hydrolyse the, abundant natural substrate DIMBOAGlc, (2-O-beta-D-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one), whose aglycone DIMBOA (2,4-hydroxy-7-methoxy-1,4-benzoxazin-3-one) is the, major defence chemical protecting seedlings and young plant parts against, herbivores and other pests. The two isoenzymes hydrolyse DIMBOAGlc with, similar kinetics but differ from each other and their sorghum homologues, with respect to specificity towards other substrates. To gain insights, into the mechanism of substrate (i.e. aglycone) specificity between the, two maize isoenzymes and their sorghum homologues, ZMGlu1 was produced in, Escherichia coli, purified, crystallized and its structure solved at 2.5, Angstrom resolution by X-ray ... | The maize beta-glucosidase isoenzymes ZMGlu1 and ZMGlu2 hydrolyse the, abundant natural substrate DIMBOAGlc, (2-O-beta-D-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one), whose aglycone DIMBOA (2,4-hydroxy-7-methoxy-1,4-benzoxazin-3-one) is the, major defence chemical protecting seedlings and young plant parts against, herbivores and other pests. The two isoenzymes hydrolyse DIMBOAGlc with, similar kinetics but differ from each other and their sorghum homologues, with respect to specificity towards other substrates. To gain insights, into the mechanism of substrate (i.e. aglycone) specificity between the, two maize isoenzymes and their sorghum homologues, ZMGlu1 was produced in, Escherichia coli, purified, crystallized and its structure solved at 2.5, Angstrom resolution by X-ray crystallography. In addition, the complex of, ZMGlu1 with the non-hydrolysable inhibitor p-nitrophenyl, beta-D-thioglucoside was crystallized and, based on the partial electron, density, a model for the inhibitor molecule within the active site is, proposed. The inhibitor is located in a slot-like active site where its, aromatic aglycone is held by stacking interactions with Trp-378. Whereas, some of the atoms on the non-reducing end of the glucose moiety can be, modelled on the basis of the electron density, most of the inhibitor atoms, are highly disordered. This is attributed to the requirement of the enzyme, to accommodate two different species, namely the substrate in its ground, state and in its distorted conformation, for catalysis. | ||
==About this Structure== | ==About this Structure== | ||
1E1E is a | 1E1E is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Zea_mays Zea mays]. Active as [http://en.wikipedia.org/wiki/Beta-glucosidase Beta-glucosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.21 3.2.1.21] Structure known Active Sites: CNA and CNB. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1E1E OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: retention of the anomeric configuration]] | [[Category: retention of the anomeric configuration]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 13:47:50 2007'' | ||
Revision as of 14:42, 5 November 2007
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CRYSTAL STRUCTURE OF A MONOCOT (MAIZE ZMGLU1) BETA-GLUCOSIDASE
OverviewOverview
The maize beta-glucosidase isoenzymes ZMGlu1 and ZMGlu2 hydrolyse the, abundant natural substrate DIMBOAGlc, (2-O-beta-D-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one), whose aglycone DIMBOA (2,4-hydroxy-7-methoxy-1,4-benzoxazin-3-one) is the, major defence chemical protecting seedlings and young plant parts against, herbivores and other pests. The two isoenzymes hydrolyse DIMBOAGlc with, similar kinetics but differ from each other and their sorghum homologues, with respect to specificity towards other substrates. To gain insights, into the mechanism of substrate (i.e. aglycone) specificity between the, two maize isoenzymes and their sorghum homologues, ZMGlu1 was produced in, Escherichia coli, purified, crystallized and its structure solved at 2.5, Angstrom resolution by X-ray crystallography. In addition, the complex of, ZMGlu1 with the non-hydrolysable inhibitor p-nitrophenyl, beta-D-thioglucoside was crystallized and, based on the partial electron, density, a model for the inhibitor molecule within the active site is, proposed. The inhibitor is located in a slot-like active site where its, aromatic aglycone is held by stacking interactions with Trp-378. Whereas, some of the atoms on the non-reducing end of the glucose moiety can be, modelled on the basis of the electron density, most of the inhibitor atoms, are highly disordered. This is attributed to the requirement of the enzyme, to accommodate two different species, namely the substrate in its ground, state and in its distorted conformation, for catalysis.
About this StructureAbout this Structure
1E1E is a Single protein structure of sequence from Zea mays. Active as Beta-glucosidase, with EC number 3.2.1.21 Structure known Active Sites: CNA and CNB. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of a monocotyledon (maize ZMGlu1) beta-glucosidase and a model of its complex with p-nitrophenyl beta-D-thioglucoside., Czjzek M, Cicek M, Zamboni V, Burmeister WP, Bevan DR, Henrissat B, Esen A, Biochem J. 2001 Feb 15;354(Pt 1):37-46. PMID:11171077
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