Sabina R L, Magill J M, Magill C W
J Bacteriol. 1976 Nov;128(2):598-603. doi: 10.1128/jb.128.2.598-603.1976.
Hypoxanthine uptake and hypoxanthine phosphoribosyltransferase activity (EC 2.4.2.8) were determined in germinated conidia from the adenine auxotrophic strains ad-1 and ad-8 and the double mutant strain ad-1 ad-8. The mutant strain ad-1 appears to lack aminoimidazolecarboximide ribonucleotide formyltransferase (EC 2.1.2.3) or inosine 5'monophosphate cyclohydrolase (EC 3.5.1.10) activities, or both, whereas the ad-8 strain lacks adenylosuccinate synthase activity (EC 6.3.4.4). Normal (or wild-type) hypoxanthine transport capacity was found to the ad-1 conidia, whereas the ad-8 strains failed to take up any hypoxanthine. The double mutant strains showed intermediate transport capacities. Similar results were obtained for hypoxanthine phosphoribosyl-transferase activity assayed in germinated conidia. The ad-1 strain showed greatest activity, the ad-8 strain showed the least activity, and the double mutant strain showed intermediate activity levels. Ion-exchange chromatography of the growth media revealed that in the presence of NH+/4, the ad-8 strain excreted hypoxanthine or inosine, the ad-1 strain did not excrete any purines, and the ad-1 ad-8 double mutant strain excreted uric acid. In the absence of NH+/4, none of the strains excreted any detectable purine compounds.
在腺嘌呤营养缺陷型菌株ad-1和ad-8以及双突变菌株ad-1 ad-8的萌发分生孢子中测定了次黄嘌呤摄取和次黄嘌呤磷酸核糖基转移酶活性（EC 2.4.2.8）。突变菌株ad-1似乎缺乏氨基咪唑甲酰胺核糖核苷酸甲酰基转移酶（EC 2.1.2.3）或肌苷5'-单磷酸环水解酶（EC 3.5.1.10）活性，或两者皆缺，而ad-8菌株缺乏腺苷酸琥珀酸合酶活性（EC 6.3.4.4）。发现ad-1分生孢子具有正常（或野生型）的次黄嘌呤转运能力，而ad-8菌株无法摄取任何次黄嘌呤。双突变菌株表现出中等的转运能力。在萌发分生孢子中测定的次黄嘌呤磷酸核糖转移酶活性也得到了类似的结果。ad-1菌株活性最高，ad-8菌株活性最低，双突变菌株活性处于中等水平。对生长培养基进行离子交换色谱分析表明，在存在NH₄⁺的情况下，ad-8菌株分泌次黄嘌呤或肌苷，ad-1菌株不分泌任何嘌呤，而ad-1 ad-8双突变菌株分泌尿酸。在不存在NH₄⁺的情况下，所有菌株均未分泌任何可检测到的嘌呤化合物。
