1qba: Difference between revisions

Revision as of 15:37, 21 February 2008

BACTERIAL CHITOBIASE, GLYCOSYL HYDROLASE FAMILY 20

OverviewOverview

Chitin, the second most abundant polysaccharide on earth, is degraded by chitinases and chitobiases. The structure of Serratia marcescens chitobiase has been refined at 1.9 A resolution. The mature protein is folded into four domains and its active site is situated at the C-terminal end of the central (beta alpha)8-barrel. Based on the structure of the complex with the substrate disaccharide chitobiose, we propose an acid-base reaction mechanism, in which only one protein carboxylate acts as catalytic acid, while the nucleophile is the polar acetamido group of the sugar in a substrate-assisted reaction. The structural data lead to the hypothesis that the reaction proceeds with retention of anomeric configuration. The structure allows us to model the catalytic domain of the homologous hexosaminidases to give a structural rationale to pathogenic mutations that underlie Tay-Sachs and Sandhoff disease.

About this StructureAbout this Structure

1QBA is a Single protein structure of sequence from Serratia marcescens with as ligand. Active as Beta-N-acetylhexosaminidase, with EC number 3.2.1.52 Full crystallographic information is available from OCA.

ReferenceReference

Bacterial chitobiase structure provides insight into catalytic mechanism and the basis of Tay-Sachs disease., Tews I, Perrakis A, Oppenheim A, Dauter Z, Wilson KS, Vorgias CE, Nat Struct Biol. 1996 Jul;3(7):638-48. PMID:8673609

Page seeded by OCA on Thu Feb 21 14:37:50 2008

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OCA

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-[[Image:1qba.gif|left|200px]]<br /><applet load="1qba" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1qba.gif|left|200px]]<br /><applet load="1qba" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1qba, resolution 1.85&Aring;" />
 '''BACTERIAL CHITOBIASE, GLYCOSYL HYDROLASE FAMILY 20'''<br />
 ==Overview==
-Chitin, the second most abundant polysaccharide on earth, is degraded by, chitinases and chitobiases. The structure of Serratia marcescens, chitobiase has been refined at 1.9 A resolution. The mature protein is, folded into four domains and its active site is situated at the C-terminal, end of the central (beta alpha)8-barrel. Based on the structure of the, complex with the substrate disaccharide chitobiose, we propose an, acid-base reaction mechanism, in which only one protein carboxylate acts, as catalytic acid, while the nucleophile is the polar acetamido group of, the sugar in a substrate-assisted reaction. The structural data lead to, the hypothesis that the reaction proceeds with retention of anomeric, configuration. The structure allows us to model the catalytic domain of, the homologous hexosaminidases to give a structural rationale to, pathogenic mutations that underlie Tay-Sachs and Sandhoff disease.
+Chitin, the second most abundant polysaccharide on earth, is degraded by chitinases and chitobiases. The structure of Serratia marcescens chitobiase has been refined at 1.9 A resolution. The mature protein is folded into four domains and its active site is situated at the C-terminal end of the central (beta alpha)8-barrel. Based on the structure of the complex with the substrate disaccharide chitobiose, we propose an acid-base reaction mechanism, in which only one protein carboxylate acts as catalytic acid, while the nucleophile is the polar acetamido group of the sugar in a substrate-assisted reaction. The structural data lead to the hypothesis that the reaction proceeds with retention of anomeric configuration. The structure allows us to model the catalytic domain of the homologous hexosaminidases to give a structural rationale to pathogenic mutations that underlie Tay-Sachs and Sandhoff disease.
 ==About this Structure==
-QBA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Serratia_marcescens Serratia marcescens] with SO4 as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Beta-N-acetylhexosaminidase Beta-N-acetylhexosaminidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.52 3.2.1.52] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1QBA OCA].
+QBA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Serratia_marcescens Serratia marcescens] with <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Beta-N-acetylhexosaminidase Beta-N-acetylhexosaminidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.52 3.2.1.52] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QBA OCA].
 ==Reference==
@@ Line 18: / Line 18: @@
 [[Category: Perrakis, A.]]
 [[Category: Tews, I.]]
-[[Category: Vorgias, C.E.]]
+[[Category: Vorgias, C E.]]
-[[Category: Wilson, K.S.]]
+[[Category: Wilson, K S.]]
 [[Category: SO4]]
 [[Category: ba8-barrel]]
@@ Line 26: / Line 26: @@
 [[Category: glycosyl hydrolase]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 00:33:14 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:37:50 2008''