Pulsed high-field gradient in vivo NMR spectroscopy to measure diffusional water permeability in Corynebacterium glutamicum.
Pulsed high-field gradient in vivo NMR spectroscopy to measure diffusional water permeability in Corynebacterium glutamicum.
复制标题
脉冲高场梯度体内核磁共振波谱测量谷氨酸棒杆菌的扩散水渗透性。
作者：
S. Schoberth;N. Bär;R. Krämer;J. Kärger
脉冲高场梯度在体内核磁共振光谱被用来测量扩散水渗透性的革兰氏阳性细菌谷氨酸棒杆菌的细胞悬浮液。两个不同的区域的水的流动性进行了检测。一种是由表观自扩散系数D（1 app）=（4.6-12.7）× 10（-8）cm（2）s（-1）表征的，取决于观察时间t。另一个区域的特征为D（2）= 1.4 × 10（-5）cm（2）s（-1）。D（2）值与H2O在自由水中和细胞外生物液中的扩散系数相似。对于较慢的过程（D（1）），可以证明限制扩散。这归因于细胞的细胞质。C.谷氨酸的浓度为（4.8+/-0.4 x10（-3）cm s（-1）。它有利地与人类红细胞的值相比，是高约100倍的扩散渗透性相比，乙醇，P（d乙醇），在运动发酵单胞菌。加入真核生物中的水通道抑制剂HgCl_2，降低了C.谷氨酸大约8倍。据我们所知，这些是第一次对原核生物中的水运输进行功能性研究，并获得了定量数据，即，通过D（H2O）和P（d H2O）表示的跨膜水渗透性。
Pulsed high-field gradient in vivo NMR spectroscopy was used to measure diffusional water permeability in cell suspensions of the Gram-positive bacterium Corynebacterium glutamicum. Two different regions of H2O mobility were detected. One was characterized by the apparent coefficient of self-diffusion, D(1 app) = (4.6-12.7)x10(-8) cm(2) s(-1), depending on the observation time t. The other region was characterized by D(2) = 1.4x10(-5) cm(2) s(-1). The value of D(2) was similar to the diffusion coefficient of H2O in free water and in extracellular biological fluids. Restricted diffusion could be demonstrated for the slower process (D(1)). It was attributed to the cytoplasm of the cells. The membrane permeability, P(d H2O), for C. glutamicum was (4.8+/-0.4)x10(-3) cm s(-1). It compared favorably with values reported for human erythrocytes and was higher by a factor of about 100 compared to the diffusional permeability for ethanol, P(d ethanol), in Zymomonas mobilis. Addition of HgCl2, a water channel inhibitor in eukaryotes, decreased P(d H2O) in C. glutamicum by a factor of approximately 8. To our knowledge, these are the first functional studies of water transport in prokaryotes that yielded quantitative data, viz., transmembrane water permeability expressed through D(H2O) and P(d H2O).