THE GAS-PERMEABILITY COEFFICIENT OF THE CYANOBACTERIAL GAS VESICLE WALL
THE GAS-PERMEABILITY COEFFICIENT OF THE CYANOBACTERIAL GAS VESICLE WALL
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DOI：
10.1099/00221287-138-4-837
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发表时间：
1992-04-01
期刊：
影响因子：
--
通讯作者：
GRIFFEL, DH
中科院分区：
文献类型：
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作者：
WALSBY, AE;REVSBECH, NP;GRIFFEL, DH
蓝藻气体囊泡壁的气体渗透系数是通过将气体囊泡膜中氧气的浓度梯度与氧气气氛上支撑的琼脂底层膜中的浓度梯度进行比较来确定的。用氧微电极测定梯度。水性琼脂中的梯度值为悬浮液中的0.81，其中气泡占总体积的0.35。由此计算出氧气通过气囊的名义扩散率相当于水中扩散率的 0.53。计算出气体囊泡膜的渗透系数为 kappa = 32 mm s-1，扩散填充气体囊泡的速率系数为 alpha = 2.4 x 10(6) s-1，气体平衡进入气体囊泡的折叠时间为 t(e) = 0.4-mu-s。渗透系数比之前压力上升实验设定的最小值高出约100倍，证实了气囊不能储存气体。然而，测量结果还表明，随机取向的气体囊泡不会提供比水中扩散率更高的扩散通道，尽管长轴平行于扩散梯度取向的一层气体囊泡将提供高出3.5倍的扩散率。扩散率的确定是通过基于扩散方程的理论进行的，该理论可用于确定通过其他细胞器的扩散率。
The gas permeability coefficient of the cyanobacterial gas vesicle wall has been determined by comparing the concentration gradient of oxygen gas in a film of gas vesicles with the gradient in an underlying film of agar supported over an oxygen atmosphere. The gradients were determined with an oxygen microelectrode. The value of the gradient in aqueous agar was 0.81 of that in a suspension in which gas vesicles occupied 0.35 of the total volume. From this it was calculated that the notional diffusivity of oxygen through the gas vesicle was equivalent to 0.53 of the diffusivity in water. The permeability coefficient of the gas vesicle membrane is calculated to be kappa = 32 mm s-1, the rate coefficient for filling the gas vesicle by diffusion is alpha = 2.4 x 10(6) s-1 and the folding time for equilibration of gas into a gas vesicle is t(e) = 0.4-mu-s. The permeability coefficient is about 100-fold higher than the minimum value set by previous pressure rise experiments, and confirms that gas vesicles could not store gas. The measurements also show, however, that randomly oriented gas vesicles would not provide a diffusion channel with a diffusivity higher than that in water, although a layer of gas vesicles oriented with their long axes parallel to the diffusion gradient would provide a diffusivity 3.5-fold higher. The determination of the diffusivity was made with a theory, based on diffusion equations, which can be used in the determination of the diffusivity through other cell organelles.