Abstract：
The nonequilibrium coupled processes of oxidation and ATP synthesis in the fundamental process of oxidative phosphorylation (OXPHOS) are of vital importance in biosystems. These coupled chemical reaction and transport bioenergetic processes using the OXPHOS pathway meet >90% of the ATP demand in aerobic systems. On the basis of experimentally determined thermodynamic OXPHOS flux-force relationships and biochemical data for the ternary system of oxidation, ion transport, and ATP synthesis, the Onsager phenomenological coefficients have been computed, including an estimate of error. A new biothermokinetic theory of energy coupling has been formulated and on its basis the thermodynamic parameters, such as the overall degree of coupling, q and the phenomenological stoichiometry, Z of the coupled system have been evaluated. The amount of ATP produced per oxygen consumed, i.e. the actual, operating P/O ratio in the biosystem, the thermodynamic efficiency of the coupled reactions, η, and the Gibbs free energy dissipation, Φ have been calculated and shown to be in agreement with experimental data. At the concentration gradients of ADP and ATP prevailing under state 3 physiological conditions of OXPHOS that yield Vmax rates of ATP synthesis, a maximum in Φ of ∼0.5J(hmgprotein)-1, corresponding to a thermodynamic efficiency of ∼60% for oxidation on succinate, has been obtained. Novel mechanistic insights arising from the above have been discussed. This is the first report of a 3 × 3 system of coupled chemical reactions with transport in a biological context in which the phenomenological coefficients have been evaluated from experimental data.
摘要：
在氧化磷酸化（OXPHOS）的基本过程中，氧化和ATP合成的非平衡耦合过程在生物系统中至关重要。使用OXPHOS途径的这些耦合的化学反应和运输生物能量过程满足有氧系统中>90%的ATP需求。根据实验确定的热力学OXPHOS通量-力关系和三元氧化系统的生化数据，离子传输，和ATP合成，已经计算了Onsager现象学系数，包括对误差的估计。建立了一种新的能量耦合的生物热动力学理论，并在其热力学参数的基础上，例如整体耦合程度，和现象学的化学计量学，对耦合系统进行了评估。每消耗氧气产生的ATP量，即实际的，生物系统中的操作P/O比，耦合反应的热力学效率，,和吉布斯自由能量耗散，已经计算并显示与实验数据一致。在OXPHOS状态3生理条件下ADP和ATP的浓度梯度下，产生ATP合成速率，的最大值，对应于琥珀酸盐氧化的热力学效率，已获得。已经讨论了由上述引起的新的机械见解。这是在生物学环境中3×3耦合化学反应与运输的系统的第一份报告，其中现象学系数已根据实验数据进行了评估。
