Use of trypsin and lipoamidase to study the role of lipoic acid moieties in the pyruvate and .alpha.-ketoglutarate dehydrogenase complexes of Escherichia coli
| Autor: | Dennis M. Bleile, Larry R. Stepp, Donald K. McRorie, Flora H. Pettit, Lester J. Reed |
|---|---|
| Rok vydání: | 1981 |
| Předmět: |
chemistry.chemical_classification
Binding Sites Thioctic Acid Ketone Oxidoreductases Pyruvate Dehydrogenase Complex Dehydrogenase Trypsin medicine.disease_cause Pyruvate dehydrogenase complex Biochemistry Amidohydrolases Kinetics Lipoic acid chemistry.chemical_compound Enzyme chemistry Escherichia coli medicine Ketoglutarate Dehydrogenase Complex Dihydrolipoyl transacetylase Oxoglutarate dehydrogenase complex medicine.drug |
| Zdroj: | Biochemistry. 20:4555-4560 |
| ISSN: | 1520-4995 0006-2960 |
| Popis: | The relationships between release of (3)H-labeled lipoyl moieties by trypsin and lipoamidase and accompanying loss of overall enzymatic activity of the Escherichia coli pyruvate and alpha-ketoglutarate dehydrogenase complexes were studied. Trypsin releases lipoyl domains together with their covalently attached lipoyl moieties from the "inner" core of the dihydrolipoyl transacetylase and the dihydrolipoyl transsuccinylase whereas lipoamidase releases only the lipoyl moieties. The results show that release of lipoyl domains by trypsin and release of lipoyl moieties by lipoamidase proceeded at faster rates than the accompanying loss of overall activity of the two complexes. Trypsin released about half of the lipoyl domains in the pyruvate dehydrogenase complex without significant effect on the overall activity. A model is presented to explain these and other observations on active-site coupling via lipoyl moieties. |
| Databáze: | OpenAIRE |
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