荧光假单胞菌细胞和膜囊泡对α-氨基异丁酸的转运
Transport of alpha-aminoisobutyrate by cells and membrane vesicles of Pseudomonas fluorescens.
作者信息
Stephenson M C, Midgley M, Dawes E A
出版信息
Biochim Biophys Acta. 1978 Jun 2;509(3):519-36. doi: 10.1016/0005-2736(78)90245-6.
The transport of alpha-aminoisobutyrate into Pseudomonas fluorescens NCIB 8865 and membrane vesicles prepared from this organism has been studied. Uptake by cells was mediated by two active transport systems with different apparent Km values, while transport into membrane vesicles was mediated by a single component. The effect of inhibitors on the energy-coupling mechanism for alpha-aminoisobutyrate transport in these systems suggests that a membrane potential may play a significant role in supporting alpha-aminoisobutyrate transport. The magnitude of the membrane potential in the vesicle system, and the sensitivity of its generation to inhibitors, has been measured using 137Cs in the presence of valinomycin. Direct attempts to demonstrate a protonsymport mechanism for alpha-aminoisobutyrate transport were negative.
对α-氨基异丁酸转运至荧光假单胞菌NCIB 8865以及由该菌株制备的膜囊泡的过程进行了研究。细胞摄取由两个具有不同表观Km值的主动转运系统介导，而转运至膜囊泡则由单一成分介导。抑制剂对这些系统中α-氨基异丁酸转运的能量偶联机制的影响表明，膜电位可能在支持α-氨基异丁酸转运中发挥重要作用。在缬氨霉素存在的情况下，使用137Cs测量了囊泡系统中膜电位的大小及其产生对抑制剂的敏感性。直接尝试证明α-氨基异丁酸转运的质子同向转运机制的结果为阴性。
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