Delta-aminolevulinate dehydratase from free-living Rhizobium
1. 1. δ-Aminolevulinate-dehydratase (ALA-D) from Rhizobium japonicum and Rhizobium meliloti was isolated and some properties were studied. 2. 2. The enzyme from both strains require DTT to maintain full activity and a concentration of about 8 mM is necessary for its maximum expression. Thiol inactiv...
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| Autores principales: | , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_0020711X_v24_n11_p1841_DeBonis |
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| Sumario: | 1. 1. δ-Aminolevulinate-dehydratase (ALA-D) from Rhizobium japonicum and Rhizobium meliloti was isolated and some properties were studied. 2. 2. The enzyme from both strains require DTT to maintain full activity and a concentration of about 8 mM is necessary for its maximum expression. Thiol inactivating compounds and heavy metals ions such as Pb2+ and Cd2+ inactivate ALA-D. 3. 3. The enzyme exhibits Michaelis-Menten kinetics and has an apparent Km of 0.095 and 0.1-0.37 mM for Rhizobium japonicum and Rhizobium meliloti respectively. 4. 4. For both strains the pH profiles show a well denned maximum at about 7.2-7.6 and a second broad peak or shoulder in the range of pH 9-10. 5. 5. ALA-D from Rhizobium does not appear to be a heat stable enzyme as it happens to be in other sources. © 1992. |
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