An arginine/ornithine exchange system in Spiroplasma melliferum
An arginine/ornithine exchange system in Spiroplasma melliferum
复制标题
蜜蜂螺原体中的精氨酸/鸟氨酸交换系统
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
S. Rottem
中科院分区：
文献类型：
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作者：
I. Shirazi;M. Tarshis;S. Rottem
蜜蜂螺原体细胞通过精氨酸二水解酶途径利用精氨酸。完整细胞对l -精氨酸的摄取是一个饱和过程，与时间和精氨酸浓度（Km）有关
Spiroplasma melliferum cells utilize arginine via the arginine dihydrolase pathway. L-Arginine uptake by intact cells was a saturable process both as a function of time and arginine concentration (Km
= 40 μM). Uptake was not affected by pH in the range pH 5.0-8.0, or by L-citrulline, D-arginine, L-histidine or L-canavanine at concentrations tenfold higher than that of L-arginine. In contrast, L-arginine uptake was markedly inhibited by L-ornithine and partially inhibited by L-lysine. Uptake was neither affected by protonophores nor by cation ionophores, but was inhibited by protease treatment or by the sulfhydryl reagents p-chloromercuribenzoate or N-ethylmaleimide. Sealed membrane vesicles prepared by fusing isolated S. melliferum membranes with asolectin-cholesterol vesicles catalysed a rapid exchange (t1/2 = 1 min) between arginine and ornithine. Exchange did not require ATP and could be demonstrated in both directions, i.e. with either arginine or ornithine trapped within vesicles. These observations suggest that the driving forces for arginine uptake by whole cells are the concentration gradients of arginine and ornithine formed by arginine metabolism.