Experiments show that macromolecular crowding modestly reduces the size ofintrinsically disordered proteins (IDPs) even at volume fraction ($\phi$)similar to that in the cytosol whereas DNA undergoes a coil-to-globuletransition at very small $\phi$. We show using a combination of scalingarguments and simulations that the polymer size $\overline{R}_g(\phi)$ dependson $x = \overline{R}_g(0)/D$ where $D$ is the $\phi$-dependent distance betweenthe crowders. If $x\lesssim \mathcal{O}(1)$, there is only a small decrease in$\overline{R}_g(\phi)$ as $\phi$ increases. When $x\gg \mathcal{O}(1)$, acooperative coil-to-globule transition is induced. Our theory quantitativelyexplains a number of experiments.
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机译：实验表明，即使在体积分数（$ \ phi $）类似于细胞质中，大分子拥挤也会适度减少内在无序蛋白（IDPs）的大小，而DNA在非常小的$ \ phi $时会发生线圈到球的转变。我们结合比例缩放参数和模拟显示，聚合物大小$ \ overline {R} _g（\ phi）$取决于$ x = \ overline {R} _g（0）/ D $，其中$ D $是$ \ phi拥挤者之间取决于美元的距离。如果$ x \ lesssim \ mathcal {O}（1）$，则随着$ \ phi $的增加，$ \ overline {R} _g（\ phi）$只会小幅减少。当$ x \ gg \ mathcal {O}（1）$时，引起了线圈到球的协作过渡。我们的理论定量地解释了许多实验。
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