Rothschild K J, Ellias S A, Essig A, Stanley H E
Biophys J. 1980 May;30(2):209-30. doi: 10.1016/S0006-3495(80)85090-9.
The linear phenomenological equations of nonequilibrium thermodynamics are limited theoretically to near equilibrium although a number of biological systems have been shown to exhibit a "linear" relationship between steady-state flows and conjugate thermodynamic forces outside the range of equilibrium. We have found a multidimensional inflection point which can exist well outside the range of equilibrium around with enzyme-catalyzed reactions exhibit "linear" behavior between the logarithm of reactant concentrations and enzyme catalyzed flows. A set of sufficient conditions has been derived which can be applied to any enzyme mechanism to determine whether a multidimensional inflection point exists. The conditions do not appear overly restrictive and may be satisfied by a large variety of coupled enzyme reactions. It is thus possible that the linearity observed in some biological systems may be explained in terms of enzyme operating near this multidimensional point.
非平衡态热力学的线性唯象方程理论上仅限于接近平衡的情况，尽管已表明许多生物系统在平衡范围之外的稳态流与共轭热力学力之间呈现出“线性”关系。我们发现了一个多维拐点，它可以存在于平衡范围之外，在该拐点附近，酶催化反应在反应物浓度的对数与酶催化流之间呈现“线性”行为。已经推导出一组充分条件，可应用于任何酶机制以确定是否存在多维拐点。这些条件似乎并非过度严格，并且可能被多种耦合酶反应所满足。因此，在某些生物系统中观察到的线性关系有可能根据在这个多维点附近起作用的酶来解释。
