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Mouse Galactocerebrosidase complexed with 1-deoxy-galacto-nojirimycin DGJ
Structural highlights
DiseaseGALC_MOUSE Defects in Galc are the cause of the 'twitcher' phenotype; an autosomal recessive leukodystrophy similar to the human disease (Krabbe disease). This deficiency results in the insufficient catabolism of several galactolipids that are important in the production of normal myelin. FunctionGALC_MOUSE Hydrolyzes the galactose ester bonds of galactosylceramide, galactosylsphingosine, lactosylceramide, and monogalactosyldiglyceride. Enzyme with very low activity responsible for the lysosomal catabolism of galactosylceramide, a major lipid in myelin, kidney and epithelial cells of small intestine and colon.[1] Publication Abstract from PubMedKrabbe disease is a devastating neurodegenerative disorder characterized by rapid demyelination of nerve fibers. This disease is caused by defects in the lysosomal enzyme beta-galactocerebrosidase (GALC), which hydrolyzes the terminal galactose from glycosphingolipids. These lipids are essential components of eukaryotic cell membranes: substrates of GALC include galactocerebroside, the primary lipid component of myelin, and psychosine, a cytotoxic metabolite. Mutations of GALC that cause misfolding of the protein may be responsive to pharmacological chaperone therapy (PCT), whereby small molecules are used to stabilize these mutant proteins, thus correcting trafficking defects and increasing residual catabolic activity in cells. Here we describe a new approach for the synthesis of galacto-configured azasugars and the characterization of their interaction with GALC using biophysical, biochemical and crystallographic methods. We identify that the global stabilization of GALC conferred by azasugar derivatives, measured by fluorescence-based thermal shift assays, is directly related to their binding affinity, measured by enzyme inhibition. X-ray crystal structures of these molecules bound in the GALC active site reveal which residues participate in stabilizing interactions, show how potency is achieved and illustrate the penalties of aza/iminosugar ring distortion. The structure-activity relationships described here identify the key physical properties required of pharmacological chaperones for Krabbe disease and highlight the potential of azasugars as stabilizing agents for future enzyme replacement therapies. This work lays the foundation for new drug-based treatments of Krabbe disease. Azasugar inhibitors as pharmacological chaperones for Krabbe disease.,Hill CH, Viuff AH, Spratley SJ, Salamone S, Christensen SH, Read RJ, Moriarty NW, Jensen HH, Deane JE Chem Sci. 2015 May 20;6(5):3075-3086. Epub 2015 Mar 30. PMID:26029356[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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