Juretić D, Westerhoff H V
Uniformed Services University of the Health Sciences, Bethesda, MD 20814.
Biophys Chem. 1987 Oct;28(1):21-34. doi: 10.1016/0301-4622(87)80072-8.
For two models of biological free-energy transducers, it is investigated how free-energy dissipation and efficiency vary as (i) the demand for output free energy, (ii) the input free energy or (iii) the properties of the transducers themselves, are varied. One model is representative of near-equilibrium free-energy transducers in general, the other is a special case of far-from-equilibrium free-energy transduction, reminiscent of proton pumping by bacteriorhodopsin. It turns out that the relationship between efficiency and free-energy dissipation depends strongly on what varies. In some cases, free-energy dissipation increases as the efficiency increases. It is suggested that this is one reason why biological evolution has not resulted in high efficiencies and low rates of free-energy dissipation. For the near-equilibrium free-energy transducer, the free-energy dissipation at the static head steady state is minimal with respect to variations in the output force. For the far-from-equilibrium model (of bacteriorhodopsin), the static head does not correspond to such a minimum, if that free-energy transducer slips.
对于两种生物自由能转换器模型，研究了自由能耗散和效率如何随着以下因素的变化而变化：（i）输出自由能需求；（ii）输入自由能；或（iii）转换器自身的特性。一种模型总体上代表近平衡自由能转换器，另一种是远离平衡自由能转换的特殊情况，让人联想到细菌视紫红质的质子泵浦。结果表明，效率与自由能耗散之间的关系很大程度上取决于变化的因素。在某些情况下，自由能耗散随着效率的提高而增加。有人认为，这是生物进化未导致高效率和低自由能耗散率的原因之一。对于近平衡自由能转换器，静态水头稳态下的自由能耗散相对于输出力的变化是最小的。对于（细菌视紫红质的）远离平衡模型，如果该自由能转换器发生滑动，静态水头并不对应于这样的最小值。
