1o7a
From Proteopedia
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==Overview== | ==Overview== | ||
| - | Human lysosomal beta-hexosaminidases are dimeric enzymes composed of alpha | + | Human lysosomal beta-hexosaminidases are dimeric enzymes composed of alpha and beta-chains, encoded by the genes HEXA and HEXB. They occur in three isoforms, the homodimeric hexosaminidases B (betabeta) and S (alphaalpha), and the heterodimeric hexosaminidase A (alphabeta), where dimerization is required for catalytic activity. Allelic variations in the HEXA and HEXB genes cause the fatal inborn errors of metabolism Tay-Sachs disease and Sandhoff disease, respectively. Here, we present the crystal structure of a complex of human beta-hexosaminidase B with a transition state analogue inhibitor at 2.3A resolution (pdb 1o7a). On the basis of this structure and previous studies on related enzymes, a retaining double-displacement mechanism for glycosyl hydrolysis by beta-hexosaminidase B is proposed. In the dimer structure, which is derived from an analysis of crystal packing, most of the mutations causing late-onset Sandhoff disease reside near the dimer interface and are proposed to interfere with correct dimer formation. The structure reported here is a valid template also for the dimeric structures of beta-hexosaminidase A and S. |
==Disease== | ==Disease== | ||
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[[Category: sphingolipid degradation]] | [[Category: sphingolipid degradation]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:14:18 2008'' |
Revision as of 12:14, 21 February 2008
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HUMAN BETA-HEXOSAMINIDASE B
Contents |
Overview
Human lysosomal beta-hexosaminidases are dimeric enzymes composed of alpha and beta-chains, encoded by the genes HEXA and HEXB. They occur in three isoforms, the homodimeric hexosaminidases B (betabeta) and S (alphaalpha), and the heterodimeric hexosaminidase A (alphabeta), where dimerization is required for catalytic activity. Allelic variations in the HEXA and HEXB genes cause the fatal inborn errors of metabolism Tay-Sachs disease and Sandhoff disease, respectively. Here, we present the crystal structure of a complex of human beta-hexosaminidase B with a transition state analogue inhibitor at 2.3A resolution (pdb 1o7a). On the basis of this structure and previous studies on related enzymes, a retaining double-displacement mechanism for glycosyl hydrolysis by beta-hexosaminidase B is proposed. In the dimer structure, which is derived from an analysis of crystal packing, most of the mutations causing late-onset Sandhoff disease reside near the dimer interface and are proposed to interfere with correct dimer formation. The structure reported here is a valid template also for the dimeric structures of beta-hexosaminidase A and S.
Disease
Known diseases associated with this structure: Sandhoff disease, infantile, juvenile, and adult forms OMIM:[606873], Spinal muscular atrophy, juvenile OMIM:[606873]
About this Structure
1O7A is a Single protein structure of sequence from Homo sapiens with , and as ligands. Active as Beta-N-acetylhexosaminidase, with EC number 3.2.1.52 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
The X-ray crystal structure of human beta-hexosaminidase B provides new insights into Sandhoff disease., Maier T, Strater N, Schuette CG, Klingenstein R, Sandhoff K, Saenger W, J Mol Biol. 2003 May 2;328(3):669-81. PMID:12706724
Page seeded by OCA on Thu Feb 21 14:14:18 2008
Categories: Beta-N-acetylhexosaminidase | Homo sapiens | Single protein | Klingenstein, R. | Maier, T. | Saenger, W. | Sandhoff, K. | Schuette, C. | Strater, N. | EDO | GDL | NAG | Ba8-barrel | Glycosidase | Glycosyl hydrolase | Hexosaminidase | Lysosomal | Sandhoff disease | Sphingolipid degradation
