Enzymes
UniProtKB help_outline | 2 proteins |
Reaction participants Show >> << Hide
- Name help_outline a globoside Gb3Cer Identifier CHEBI:88154 Charge 0 Formula C22H37NO18R2 SMILEShelp_outline [C@@H]1([C@@H]([C@H]([C@@H]([C@H](O1)CO)O[C@H]2[C@@H]([C@H]([C@H]([C@H](O2)CO)O[C@@H]3[C@@H]([C@H]([C@H]([C@H](O3)CO)O)O)O)O)O)O)O)OC[C@@H]([C@@H](*)O)NC(=O)* 2D coordinates Mol file for the small molecule Search links Involved in 5 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H2O Identifier CHEBI:15377 (Beilstein: 3587155; CAS: 7732-18-5) help_outline Charge 0 Formula H2O InChIKeyhelp_outline XLYOFNOQVPJJNP-UHFFFAOYSA-N SMILEShelp_outline [H]O[H] 2D coordinates Mol file for the small molecule Search links Involved in 6,048 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline a β-D-galactosyl-(1→4)-β-D-glucosyl-(1↔1)-ceramide Identifier CHEBI:79208 Charge 0 Formula C16H27NO13R2 SMILEShelp_outline OC[C@H]1O[C@@H](O[C@H]2[C@H](O)[C@@H](O)[C@H](OC[C@H](NC([*])=O)[C@H](O)[*])O[C@@H]2CO)[C@H](O)[C@@H](O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 21 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline D-galactose Identifier CHEBI:4139 (Beilstein: 1281605; CAS: 10257-28-0,59-23-4) help_outline Charge 0 Formula C6H12O6 InChIKeyhelp_outline WQZGKKKJIJFFOK-SVZMEOIVSA-N SMILEShelp_outline OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 37 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:48020 | RHEA:48021 | RHEA:48022 | RHEA:48023 | |
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Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
UniProtKB help_outline |
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Publications
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Characterization of two alpha-galactosidase mutants (Q279E and R301Q) found in an atypical variant of Fabry disease.
Kase R., Bierfreund U., Klein A., Kolter T., Utsumi K., Itoh K., Sandhoff K., Sakuraba H.
The mutant products Q279E ((279)Gln to Glu) and R301Q ((301)Arg to Gln) of the X-chromosomal inherited alpha-galactosidase (EC 3.2.1. 22) gene, found in unrelated male patients with variant Fabry disease (late-onset cardiac form) were characterized. In contrast to patients with classic Fabry disea ... >> More
The mutant products Q279E ((279)Gln to Glu) and R301Q ((301)Arg to Gln) of the X-chromosomal inherited alpha-galactosidase (EC 3.2.1. 22) gene, found in unrelated male patients with variant Fabry disease (late-onset cardiac form) were characterized. In contrast to patients with classic Fabry disease, who have no detectable alpha-galactosidase activity, atypical variants have residual enzyme activity. First, the properties of insect cell-derived recombinant enzymes were studied. The K(m) and V(max) values of Q279E, R301Q, and wild-type alpha-galactosidase toward an artificial substrate, 4-methylumbelliferyl-alpha-D-galactopyranoside, were almost the same. In order to mimic intralysosomal conditions, the degradation of the natural substrate, globotriaosylceramide, by the alpha-galactosidases was analyzed in a detergent-free-liposomal system, in the presence of sphingolipid activator protein B (SAP-B, saposin B). Kinetic analysis revealed that there was no difference in the degradative activity between the mutants and wild-type alpha-galactosidase activity toward the natural substrate. Then, immunotitration studies were carried out to determine the amounts of the mutant gene products naturally occurring in cells. Cultured lymphoblasts, L-57 (Q279E) and L-148 (R301Q), from patients with variant Fabry disease, and L-20 (wild-type) from a normal subject were used. The 50% precipitation doses were 7% (L-57) and 10% (L-148) of that for normal lymphoblast L-20, respectively. The residual alpha-galactosidase activity was 3 and 5% of the normal level in L-57 and L-148, respectively. The quantities of immuno cross-reacting materials roughly correlated with the residual alpha-galactosidase activities in lymphoblast cells from the patients. Compared to normal control cells, fibroblast cells from a patient with variant Fabry disease, Q279E mutation, secreted only small amounts of alpha-galactosidase activity even in the presence of 10 mM NH(4)Cl. It is concluded that Q279E and R301Q substitutions do not significantly affect the enzymatic activity, but the mutant protein levels are decreased presumably in the ER of the cells. << Less
Biochim. Biophys. Acta 1501:227-235(2000) [PubMed] [EuropePMC]
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Only sphingolipid activator protein B (SAP-B or saposin B) stimulates the degradation of globotriaosylceramide by recombinant human lysosomal alpha-galactosidase in a detergent-free liposomal system.
Kase R., Bierfreund U., Klein A., Kolter T., Itoh K., Suzuki M., Hashimoto Y., Sandhoff K., Sakuraba H.
The degradation of globotriaosylceramide (GbO-se3Cer) by insect-cell derived recombinant human alpha-galactosidase (EC 3.2.1.22) was carried out in a detergent-free liposomal system in order to mimic intralysosomal conditions. GbOse3Cer incorporated into unilamellar liposomes was used as the subst ... >> More
The degradation of globotriaosylceramide (GbO-se3Cer) by insect-cell derived recombinant human alpha-galactosidase (EC 3.2.1.22) was carried out in a detergent-free liposomal system in order to mimic intralysosomal conditions. GbOse3Cer incorporated into unilamellar liposomes was used as the substrate, and naturally occurring sphingolipid activator proteins, rather than detergents, were used to stimulate the enzyme reaction. The degradation of GbOse3Cer was dependent on the presence of both alpha-galactosidase and sphingolipid activator protein B (SAP-B or saposin B). It proceeded optimally at pH 4.6, and was enhanced by increasing amounts of both alpha-galactosidase (0.24-24 mU/50 microliters assay) and SAP-B (0-5 micrograms/50 microliters assay). The enzyme reaction was not affected by SAP-A, SAP-C, or SAP-D. Therefore, our results indicate that only SAP-B is essential for the degradation of GbOse3Cer by alpha-galactosidase. << Less