1o7a

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spinqualitylabelsall models PDB ID 1o7a Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
, resolution 2.25Å
Sites:
Ligands:	, and
Activity:	Beta-N-acetylhexosaminidase, with EC number 3.2.1.52
Coordinates:	save as pdb, mmCIF, xml

HUMAN BETA-HEXOSAMINIDASE B

Contents 1 Overview 2 Disease 3 About this Structure 4 Reference

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. 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

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