Porphyrin biosynthesis in soybean callus. V. The porphobilinogen deaminase-uroporphyrinogen cosynthetase system. Kinetic studies
Kinetic studies were carried out using purified porphobilinogenase and deaminase preparations in the presence and absence of ammonium ions. It has been found in plots of v versus [S] that a deviation from the Michaelis-Menten hyperbola occurs with both enzymes; double-reciprocal plot...
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| Autores principales: | , |
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| Formato: | Artículo publishedVersion |
| Publicado: |
1970
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00052744_v220_n3_p552_Llambias https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_00052744_v220_n3_p552_Llambias_oai |
| Aporte de: |
| Sumario: | Kinetic studies were carried out using purified porphobilinogenase and deaminase preparations in the presence and absence of ammonium ions. It has been found in plots of v versus [S] that a deviation from the Michaelis-Menten hyperbola occurs with both enzymes; double-reciprocal plots were concave downward; Rs values were greater than 81; and in some cases the Hill coefficient was less than 1, indicating negative homotropic kinetics. Evidence also suggested that porphobilinogenase contains at least two substrate-binding sites per molecule of enzyme. It has also been found that ammonium ions act competitively on the first reaction of the porphobilinogenase. © 1970. |
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