Dept. of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India.
J Phys Chem B. 2021 Feb 25;125(7):1760-1767. doi: 10.1021/acs.jpcb.0c10350. Epub 2021 Feb 10.
In this paper, we consider a macromolecule with two competitive binding sites where a ligand can bind to and gives rise to a unicyclic reaction network consisting of four states-(i) a single state with both binding sites vacant, (ii) two states with one bound site and one free binding site, and (iii) an another single state with both sites occupied. We obtain probability densities of the time-integrated current along the clockwise direction and the dynamical activity or mean number of jumps between different states for finite times at a fast diffusion limit. On the other hand, in the diffusion-limited case, ligand diffusion between the two binding sites directly connects the mono-ligated states-changing the reaction scheme. Addition of the new reaction channel alters the precision of ligand occupancy to a single site, the mean dynamical activity, and the mean entropy production rate. All of these quantities are calculated with varying degrees of competition between the two sites for ligands, and we find that increase in the competition between the two sites decreases all above-mentioned additive functionals. The upper bound of precision associated with a single-site ligand occupancy for a diffusion-influenced reaction network is set by the mean dynamical activity (mean entropy production rate) at small (large) ligand concentrations at the steady-state limit.
在本文中，我们考虑了一种具有两个竞争结合位点的大分子，其中配体可以结合并产生一个由四个状态组成的单环反应网络-(i) 两个结合位点都为空的单一状态，(ii) 一个结合位点被占据而另一个结合位点为空的两个状态，和 (iii) 两个结合位点都被占据的另一个单一状态。我们在快扩散极限下获得了有限时间内沿顺时针方向的时间积分电流的概率密度和不同状态之间的动态活动或平均跳跃次数。另一方面，在扩散限制的情况下，两个结合位点之间的配体扩散直接连接了单配状态-改变了反应方案。新反应通道的加入改变了配体占据单个位点的精度、平均动态活性和平均熵产生率。所有这些数量都在两个位点之间的竞争程度变化下进行了计算，我们发现两个位点之间的竞争增加会降低所有上述加性函数。在扩散影响的反应网络中，与单个位点配体占有率相关的精度上限由小（大）配体浓度下的稳态限制下的平均动态活性（平均熵产生率）设定。
