Porphyrin biosynthesis-immobilized enzymes and ligands-X. A novel approach to the study of the relationship between the quaternary structure of aminolaevulinate dehydratase and its activity
1. 1. Evidence for dissociation, renaturation, re-association and re-hybridization of bovine liver aminolaevulinate dehydratase attached to Sepharose 4B is reported. 2. 2. When insolubilized enzyme was treated with 3 and 6 M urea, non covalently bound subunits were dissociated and detected in the el...
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| Autores principales: | , , , |
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| Publicado: |
1978
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| Materias: | |
| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0020711X_v9_n6_p401_DelCBatlle http://hdl.handle.net/20.500.12110/paper_0020711X_v9_n6_p401_DelCBatlle |
| Aporte de: |
| Sumario: | 1. 1. Evidence for dissociation, renaturation, re-association and re-hybridization of bovine liver aminolaevulinate dehydratase attached to Sepharose 4B is reported. 2. 2. When insolubilized enzyme was treated with 3 and 6 M urea, non covalently bound subunits were dissociated and detected in the eluate; these subunits can be re-associated into a soluble functioning enzyme with a specific activity close to that of the original pure soluble dehydratase preparation. 3. 3. After being washed with a renaturing buffer mixture, the matrix-bound subunits recovered a level of enzymatic activity equal to 50 and 20% of that of the immobilized native aminolaevulinate dehydratase. 4. 4. The reversibility of the dissociation process was investigated. Bound-subunits dehydratase can associate with nascent soluble bovine liver aminolaevulinate dehydratase subunits in situ. The product of such treatment, bound-re-associated enzyme, has the same activity as that of the original bound-dehydratase. The matrix-bound-dissociated bovine liver enzyme was also re-hybridized with soluble dehydratase subunits from E. gracilis. 5. 5. The apparent Km and optimum pH of the immobilized subunits were the same as those of the bound-octameric enzyme. 6. 6. A scheme is proposed, explaining the sequence of reactions leading from the bound-octameric dehydratase to the possible different derivatives, formed during the dissociation and re-association experiments. © 1978. |
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