Solubilisation and Properties of the Sialate-4-O-Acetyltransferase from Guinea Pig Liver
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M. Iwersen
Abstract
The O-acetylation of sialic acids turns out to be one of the most important modifications that influence the diverse biological and pathophysiological properties of glycoconjugates in animals and microorganisms. To understand the functions of this esterification, knowledge of the properties, structures and regulation of expression of the enzymes involved is essential. Attempts to solubilise, purify or clone the gene of one of the sialate-O-acetyltransferases have failed so far. Here we report on the solubilisation of the sialate 4-O-acetyltransferase from guinea pig liver, the first and essential step in the purification and molecular characterisation of this enzyme, by the zwitterionic detergent CHAPS. This enzyme Oacetylates sialic acids at C-4 both free and bound to oligosaccharides, glycoproteins and glycolipids with varying activity, however, gangliosides proved to be the best substrates. Correspondingly, a rapid enzyme test was elaborated using the ganglioside GD3. The soluble Oacetyltransferase maximally operated at 30C, pH 5.6, and 50-70 mM KCl and K2HPO4 concentrations. The Km values were 3.6 M for AcCoA and 1.2 M for GD3. CoA inhibits the enzyme with a Ki value of 14.8 M. A most important discovery enabling further enzyme purification is its need for an unknown low molecular mass and heat-stable cofactor that can be separated from the crude enzyme preparation by 30 kDa ultrafiltration.
Copyright © 2003 by Walter de Gruyter GmbH & Co. KG
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Artikel in diesem Heft
- Protein Prenyltransferases: Anchor Size, Pseudogenes and Parasites
- Redox Regulation of Cell Growth and Cell Death
- Are Histones the Targets for Flavan-3-ols (Catechins) in Nuclei?
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- Interaction of Maize Chromatin-Associated HMG Proteins with Mononucleosomes: Role of Core and Linker Histones
- Transcriptional Silencing of the TFPI-2 Gene by Promoter Hypermethylation in Choriocarcinoma Cells
- Solubilisation and Properties of the Sialate-4-O-Acetyltransferase from Guinea Pig Liver
- A Peroxidase from Lepista irina Cleaves β,β-Carotene to Flavor Compounds
- Physarum polycephalum Expresses a Dihydropteridine Reductase with Selectivity for Pterin Substrates with a 6-(1', 2-Dihydroxypropyl) Substitution
- Effects of Hydrogen Peroxide on Bovine Leukemia Virus Expression
- Ovarian Cancer Cell Proliferation and Motility Is Induced by Engagement of Integrin αvβ3/Vitronectin Interaction
- Novel Bi- and Trifunctional Inhibitors of Tumor-Associated Proteolytic Systems
- Inhibition of Intraperitoneal Tumor Growth of Human Ovarian Cancer Cells by Bi- and Trifunctional Inhibitors of Tumor-Associated Proteolytic Systems
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