Characterization of complexes formed between TSG-6 and inter-alpha-inhibitor that act as intermediates in the covalent transfer of heavy chains onto hyaluronan
| Autor: | Durba Mukhopadhyay, Anthony J. Day, Csaba Fülöp, Antony C. Willis, Caroline M. Milner, Vincent C. Hascall, Erik Fries, Marilyn S. Rugg |
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| Rok vydání: | 2005 |
| Předmět: |
Stereochemistry
Context (language use) In Vitro Techniques Biochemistry Cofactor Catalysis Cell Line Glycosaminoglycan chemistry.chemical_compound Mice Alpha-Globulins Moiety Animals Humans Sodium Hydroxide Magnesium Chondroitin sulfate Hyaluronic Acid Molecular Biology TSG-6 Manganese biology Cell Biology In vitro Recombinant Proteins Chondroitinases and Chondroitin Lyases Molecular Weight chemistry Covalent bond biology.protein Drosophila Cell Adhesion Molecules Protein Binding |
| Zdroj: | The Journal of biological chemistry. 280(27) |
| ISSN: | 0021-9258 |
| Popis: | The high molecular mass glycosaminoglycan hyaluronan (HA) can become modified by the covalent attachment of heavy chains (HCs) derived from the serum protein inter-alpha-inhibitor (IalphaI), which is composed of three subunits (HC1, HC2 and bikunin) linked together via a chondroitin sulfate moiety. The formation of HC.HA is likely to play an important role in the stabilization of HA-rich extracellular matrices in the context of inflammatory disease (e.g. arthritis) and ovulation. Here, we have characterized the complexes formed in vitro between purified human IalphaI and recombinant human TSG-6 (an inflammation-associated protein implicated previously in this process) and show that these complexes (i.e. TSG-6 x HC1 and TSG-6 x HC2) act as intermediates in the formation of HC x HA. This is likely to involve two transesterification reactions in which an ester bond linking an HC to chondroitin sulfate in intact IalphaI is transferred first onto TSG-6 and then onto HA. The formation of TSG-6 x HC1 and TSG-6 x C2 complexes was accompanied by the production of bikunin x HC2 and bikunin x HC1 by-products, respectively, which were observed to break down, releasing free bikunin and HCs. Both TSG-6 x HC formation and the subsequent HC transfer are metal ion-dependent processes; these reactions have a requirement for either Mg2+ or Mn2+ and are inhibited by Co2+. TSG-6, which is released upon the transfer of HCs from TSG-6 onto HA, was shown to combine with IalphaI to form new TSG-6 x HC complexes and thus be recycled. The finding that TSG-6 acts as cofactor and catalyst in the production of HC x HA complexes has important implications for our understanding of inflammatory and inflammation-like processes. |
| Databáze: | OpenAIRE |
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