Larsen Knud, Jochimsen Bjarne U
Department of Molecular Biology and Plant Physiology, University of Aarhus, DK-8000 Aarhus C, Denmark.
EMBO J. 1986 Jan;5(1):15-19. doi: 10.1002/j.1460-2075.1986.tb04171.x.
In soybean root nodules the enzyme uricase is expressed concomitantly with nodule development. The initial expression of this protein does not depend on active nitrogen fixation, as demonstrated by analysis of uricase activity in effective and ineffective root nodules. However, the maximal level of uricase activity is determined by the infecting Rhizobium japonicum strain. Sterile root cultures and callus tissue, devoid of the microsymbiont, were incubated at varying oxygen concentrations and analyzed for uricase activity. The specific activity of uricase was increased by lowering the oxygen concentration, with the highest activity obtained around 4-5% oxygen. The increase in uricase activity was due to increased uricase synthesis, as demonstrated by in vivo labelling of callus culture followed by immunoprecipitation with antibodies raised against highly purified nodule uricase.
在大豆根瘤中，尿酸酶随着根瘤的发育而表达。通过对有效和无效根瘤中尿酸酶活性的分析表明，这种蛋白质的初始表达并不依赖于活跃的固氮作用。然而，尿酸酶活性的最高水平由感染的日本根瘤菌菌株决定。将无菌根培养物和不含微共生体的愈伤组织在不同氧气浓度下培养，并分析尿酸酶活性。降低氧气浓度可提高尿酸酶的比活性，在氧气浓度约为4 - 5%时活性最高。尿酸酶活性的增加是由于尿酸酶合成增加，这通过对愈伤组织培养物进行体内标记，然后用针对高度纯化的根瘤尿酸酶产生的抗体进行免疫沉淀得到证明。
