5'-Methylthioadenosine phosphorylase from Caldariella acidophila. Purification and properties
| Autor: | Agata Gambacorta, Mario De Rosa, Maria Cartenì-Farina, Adriana Oliva, Giovanna Romeo, Vincenzo Zappia, Giuseppina Napolitano |
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| Přispěvatelé: | CARTENI' FARINA, M, Oliva, Adriana, Romeo, G, Napolitano, G, DE ROSA, M, Gambacorta, A, Zappia, V. |
| Jazyk: | angličtina |
| Rok vydání: | 1979 |
| Předmět: |
chemistry.chemical_classification
Adenosine Hot Temperature Thionucleosides Bacteria Chemistry Isoelectric focusing Thermophile Size-exclusion chromatography Substrate (chemistry) Biochemistry Substrate Specificity Kinetics chemistry.chemical_compound Enzyme Drug Stability Purine-Nucleoside Phosphorylase Thioether Yield (chemistry) Pentosyltransferases Methylthioinosine |
| Popis: | The occurrence of 5'-methylthioadenosine phosphorylase in Caldariella acidophila, a thermophilic bacterium growing optimally at 87 degrees C, is reported. It represents the first example in prokaryotes of a phosphoryolytic cleavage of the thioether. The reaction products, purified by ion-exchange chromatography, have been identified as 5-methylthioribose-1-phosphate and adenine by several analytical procedures. The enzyme has been purified to homogeneity in 32% yield by using DEAE-cellulose and hydroxyapatite chromatography, gel filtration and isoelectric focusing. The enzyme shows a high degree of thermophilicity, its temperature optimum being at 93 degrees C; furthermore no loss of activity is observable after exposure for 1 h at 100 degrees C. The kinetic data indicate a sequential mechanism of the reaction. The apparent Km values are 0.095 mM for 5'-methylthioadenosine and 6.1 mM for phosphate. The specificity of the reaction is rather strict. Experiments performed with analogues of the substrate, i.e. 5'-methylthioinosine, 5'-dimethylthioadenosine sulfonium salt, 5'-n-butylthioadenosine, 5'-isobutylthioadenosine, 5'-isobutylthioinosine, adenosylhomocysteine, 5'-thioethanoladenosine, adenosine, indicate the relevance of the adenine amino group and the sulfur in thioether form in the binding to the enzyme protein. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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