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| {{STRUCTURE_1o7a| PDB=1o7a | SCENE= }} | | {{STRUCTURE_1o7a| PDB=1o7a | SCENE= }} |
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| '''HUMAN BETA-HEXOSAMINIDASE B'''
| | ===HUMAN BETA-HEXOSAMINIDASE B=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12706724}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12706724 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12706724}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Sandhoff disease]] | | [[Category: Sandhoff disease]] |
| [[Category: Sphingolipid degradation]] | | [[Category: Sphingolipid degradation]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 03:28:22 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 15:17:33 2008'' |
