WINTERS R W, DELLUVA A M, DEYRUP I J, DAVIES R E
J Gen Physiol. 1962 Mar;45(4):757-75. doi: 10.1085/jgp.45.4.757.
Twice washed mitochondria from rat kidney cortex can accumulate sulfate ions from low (10(-7)M) ambient concentrations to create virtual gradients of several hundred to one. This sulfate is subsequently released. The activation energy for the uptake is 12,000 calories per mole; for release it is about 30,000 calories per mole. Variations in the sulfate concentration of the medium show that there is a straight line Freundlich adsorption isotherm over a million-fold range of concentration of sulfate in the medium. There are 9 x 10(4) sites at 10(-5)M and 9 x 10(5) sites at 10(-3)M sulfate per average single mitochondrion. Preincubation at 30 degrees C rapidly destroys the ability to accumulate sulfate. Partial protection occurs if oxidative phosphorylation is proceeding during the preincubation. The concentration of the endogenous inorganic sulfate of twice washed mitochondria is 4.2 x 10(-4) moles per liter of mitochondrial pellet water; 99.85 per cent of this endogenous sulfate is inexchangeable with external sulfate in vitro. It is all exchangeable in vivo. The pH optimum for accumulation of radiosulfate from dilute external sulfate concentrations is 5.5. These observations show that there is a delicate and specific mechanism in mitochondria from kidney cortex which accumulates sulfate. The chemical nature of the accumulated sulfate is unknown.
经两次洗涤的大鼠肾皮质线粒体能够从低浓度（10⁻⁷M）的周围环境中积累硫酸根离子，形成几百比一的虚拟梯度。随后这些硫酸根离子会被释放。摄取的活化能为每摩尔12000卡路里；释放的活化能约为每摩尔30000卡路里。培养基中硫酸根离子浓度的变化表明，在培养基中硫酸根离子浓度百万倍的范围内存在一条直线型弗罗因德利希吸附等温线。平均每个线粒体在硫酸根离子浓度为10⁻⁵M时有9×10⁴个位点，在硫酸根离子浓度为10⁻³M时有9×10⁵个位点。在30℃下预孵育会迅速破坏积累硫酸根离子的能力。如果在预孵育期间氧化磷酸化过程正在进行，则会出现部分保护作用。经两次洗涤的线粒体的内源性无机硫酸根离子浓度为每升线粒体沉淀水4.2×10⁻⁴摩尔；在体外，这种内源性硫酸根离子的99.85%与外部硫酸根离子不可交换。在体内它是完全可交换的。从稀的外部硫酸根离子浓度积累放射性硫酸根离子的最适pH为5.5。这些观察结果表明，肾皮质线粒体中存在一种精细且特异的积累硫酸根离子的机制。积累的硫酸根离子的化学性质尚不清楚。
