Purine uptake by Alcaligenes eutrophus H16 |
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Authors: | Klaus Eschmann Heinrich Kaltwasser |
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Institution: | (1) Fachrichtung Mikrobiologie der Universität des Saarlandes, Im Stadtwald, D-6600 Saarbrücken, Federal Republic of Germany |
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Abstract: | The uptake of adenine, guanine, xanthine, hypoxanthine and uric acid by whole cells was studied, using spectrophotometric techniques, 14C-labelled compounds and metabolic inhibitors. Three different non-constitutive systems were shown to maintain the uptake of adenine and that of the pairs guanine/hypoxanthine and xanthine/uric acid. —Active transport of adenine was induced by adenine only, but passive uptake was also involved. Maximum K
T values of 110–131 M were observed at the pH optimum of 8.0. —Guanine and hypoxanthine were translocated by one single mechanism as indicated by K
T and K
I values. This system was induced by both these substances but its affinity was 51/2-times higher for guanine than for hypoxanthine; it was noncompetitively stimulated by Mg2+. — A further system, induced by xanthine and uric acid, catalyzed the uptake of both these compounds. It exhibited two pH optima (at pH 6.6 and 7.9); inactivation by heat and stimulation or inhibition by several compounds indicated that two separate mechanisms might be involved in the uptake of xanthine and uric acid. |
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Keywords: | Adenine Alcaligenes eutrophus Guanine Hypoxanthine Purine uptake Uric acid Xanthine |
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