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首页> 外文期刊>Journal of bacteriology >Transport systems for branched-chain amino acids in Pseudomonas aeruginosa.
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Transport systems for branched-chain amino acids in Pseudomonas aeruginosa.

机译：铜绿假单胞菌的分支链氨基酸的运输系统。

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The cells of Pseudomonas aeruginosa showed high activity for leucine transport in the absence of Na+, giving a Km value of 0.34 microM. In the presence of Na+, however, two Km values, 0.37 microM (LIV-I system) and 7.6 microM (LIV-II system), were obtained. The former system seemed to serve not only for the entry of leucine, isoleucine, and valine, but also for that of alanine and threonine, although less effectively. However, the LIV-II system served for the entry of branched-chain amino acids only. The LIV-II system alone was operative in membrane vesicles, for the transport of branched-chain amino acids in membrane vesicles required Na+ and gave single Km values for the respective amino acids. When cells were osmotically shocked, the activity of the LIV-I system decreased, whereas the LIV-II system remained unaffected. The shock fluid from P. aeruginosa cells showed leucine-binding activity with a dissociation constant of 0.25 microM. The specificity of the activity was very similar to that of the LIV-I system. These results suggest that a leucine-binding protein(s) in the periplasmic space may be required for the transport process via the LIV-I system of P. aeruginosa.
机译：铜绿假单胞菌的细胞在不存在Na +的情况下表现出亮氨酸转运的高活性，得到Km值为0.34微米。然而，在存在Na +的存在下，获得了两公里的值，0.37微米（LIV-I系统）和7.6微米（LIV-II系统）。前者似乎不仅用于亮氨酸，异亮氨酸和缬氨酸的进入，而且还用于丙氨酸和苏氨酸的进入，尽管较少有效。然而，LIV-II系统仅用于分支链氨基酸的进入。单独的LIV-II系统在膜囊泡中可操作，用于在膜囊泡中的支链氨基酸转运所需Na +，并为各自的氨基酸产生单km值。当细胞渗透疼痛时，LIV-I系统的活性降低，而LIV-II系统仍未受到影响。来自P.铜绿假单胞菌细胞的冲击液显示出亮氨酸结合活性，其解离常数为0.25微米。活动的特异性与LIV-I系统的特异性非常相似。这些结果表明，通过P. Aeruginosa的LiV-I系统，可以需要过周质空间中的亮氨酸结合蛋白。

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