Effect of Amino Acids on the Nitrogenase System of Klebsiella pneumoniae
Effect of Amino Acids on the Nitrogenase System of Klebsiella pneumoniae
复制标题
氨基酸对肺炎克雷伯菌固氮酶系统的影响
作者：
D. C. Yoch;R. Pengra
Yoch, d.c.（南达科塔州立大学，布鲁金斯）和r.m. Pengra。氨基酸对肺炎克雷伯菌氮酶系统的影响。[j] .细菌学杂志。92:618-622。1966.研究了外源氨基酸和游离氨基酸池对肺炎克雷伯菌M5al（原增氧氧杆菌M5al）氮酶系统合成的影响。当用活性固定n2的培养物接种含有极限浓度NH4+的培养基时，观察到诱导滞后期。当在相同的氮浓度下替换单个氨基酸或氨基酸混合物时，在诱导期内生长是不间断的。看来，在氮酶系统的形成过程中，有一个或多个步骤受到NH4+的抑制，而不受氨基酸n的影响。氨基酸不仅不像NH4+那样抑制氮酶的形成，实际上还促进了氮酶的形成。似乎游离氮和氨基氮同时被使用。与N2同时作为氮源的氨基酸有：天冬氨酸、丝氨酸、苏氨酸、亮氨酸和组氨酸。在这些氨基酸中，天冬氨酸很容易被细胞吸收。在不作为直接氮源的氨基酸中，异亮氨酸不被细胞吸收。在诱导期开始和结束时测定细胞的游离氨基酸库。诱导期氨基酸池中茚三酮阳性物质耗损35%。
Yoch, D. C. (South Dakota State University, Brookings), and R. M. Pengra. Effect of amino acids on the nitrogenase system of Klebsiella pneumoniae. J. Bacteriol. 92:618–622. 1966.—The effect of exogenous amino acids and the free amino acid pool on the synthesis of the nitrogenase system of Klebsiella pneumoniae M5al (formerly Aerobacter aerogenes M5al) was investigated. When an actively N2-fixing culture was used to inoculate a medium containing a limiting concentration of NH4+, an induction lag period was observed. When either a single amino acid or a mixture of amino acids was substituted at the same nitrogen concentration, growth was uninterrupted by the induction period. It appears that a step or steps in the formation of the nitrogenase system are repressed by NH4+ and are not affected by amino acid N. The amino acids, far from repressing formation of nitrogenase as does NH4+, actually stimulate its formation. It appears that both free and amino nitrogen are used simultaneously. The amino acids that served concomitantly with N2 as a source of nitrogen were: aspartic acid, serine, threonine, leucine, and histidine. Of these amino acids, it was shown that aspartic acid is readily taken up by the cells. Of the amino acids not serving as an immediate nitrogen source, isoleucine is not taken up by the cells. The free amino acid pool of the cells was measured at the onset and termination of the induction period. Ninhydrin-positive material in the amino acid pool was depleted by 35% during the induction period.