1tr1

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{{STRUCTURE_1tr1| PDB=1tr1 | SCENE= }}
{{STRUCTURE_1tr1| PDB=1tr1 | SCENE= }}
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'''CRYSTAL STRUCTURE OF E96K MUTATED BETA-GLUCOSIDASE A FROM BACILLUS POLYMYXA, AN ENZYME WITH INCREASED THERMORESISTANCE'''
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===CRYSTAL STRUCTURE OF E96K MUTATED BETA-GLUCOSIDASE A FROM BACILLUS POLYMYXA, AN ENZYME WITH INCREASED THERMORESISTANCE===
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==Overview==
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Family 1 glycosyl hydrolases are a very relevant group of enzymes because of the diversity of biological roles in which they are involved, and their generalized occurrence in all sorts of living organisms. The biological plasticity of these enzymes is a consequence of the variety of beta-glycosidic substrates that they can hydrolyze: disaccharides such as cellobiose and lactose, phosphorylated disaccharides, cyanogenic glycosides, etc. The crystal structure of BglA, a member of the family, has been determined in the native state and complexed with gluconate ligand, at 2.4 A and 2.3 A resolution, respectively. The subunits of the octameric enzyme display the (alpha/beta)8 barrel structural fold previously reported for other family 1 enzymes. However, significant structural differences have been encountered in the loops surrounding the active-center cavity. These differences make a wide and extended cavity in BglA, which seems to be able to accommodate substrates longer than cellobiose, its natural substrate. Furthermore, a third sub-site is encountered, which might have some connection with the transglycosylating activity associated to this enzyme and its certain activity against beta-1,4 oligosaccharides composed of more than two units of glucose. The particular geometry of the cavity which contains the active center of BglA must therefore account for both, hydrolytic and transglycosylating activities. A potent and well known inhibitor of different glycosidases, D-glucono-1,5-lactone, was used in an attempt to define interactions of the substrate with specific protein residues. Although the lactone has transformed into gluconate under crystallizing conditions, the open species still binds the enzyme, the conformation of its chain mimicking the true inhibitor. From the analysis of the enzyme-ligand hydrogen bonding interactions, a detailed picture of the active center can be drawn, for a family 1 enzyme. In this way, Gln20, His121, Tyr296, Glu405 and Trp406 are identified as determinant residues in the recognition of the substrate. In particular, two bidentate hydrogen bonds made by Gln20 and Glu405, could conform the structural explanation for the ability of most members of the family for displaying both, glucosidase and galactosidase activity.
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(as it appears on PubMed at http://www.pubmed.gov), where 9466926 is the PubMed ID number.
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{{ABSTRACT_PUBMED_9466926}}
==About this Structure==
==About this Structure==
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[[Category: Family 1 beta-glucosidase]]
[[Category: Family 1 beta-glucosidase]]
[[Category: Increased thermoresistance]]
[[Category: Increased thermoresistance]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 10:16:26 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 13:24:47 2008''

Revision as of 10:24, 27 July 2008

Image:1tr1.png

Template:STRUCTURE 1tr1

CRYSTAL STRUCTURE OF E96K MUTATED BETA-GLUCOSIDASE A FROM BACILLUS POLYMYXA, AN ENZYME WITH INCREASED THERMORESISTANCE

Template:ABSTRACT PUBMED 9466926

About this Structure

1TR1 is a Single protein structure of sequence from Paenibacillus polymyxa. Full crystallographic information is available from OCA.

Reference

Crystal structure of beta-glucosidase A from Bacillus polymyxa: insights into the catalytic activity in family 1 glycosyl hydrolases., Sanz-Aparicio J, Hermoso JA, Martinez-Ripoll M, Lequerica JL, Polaina J, J Mol Biol. 1998 Jan 23;275(3):491-502. PMID:9466926

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