排斥體積效應對具有均勻自發曲率的二維半柔 軟生物高分子的彈性性質之影響

Effect of excluded volume on the elasticity of two-dimensional semiflexible biopolymers with constant spontaneous curvature

何柏樺(Bo-hua Ho)

指導教授 ： 周子聰

淡江大學/理學院/物理學系碩士班/碩士(2008年)

https://doi.org/10.6846/TKU.2008.00767

摘要

我們研究了在有限溫度下具有自發曲率的二維半柔軟生物高分
子的力學性質。我們發現在我們的模型中，當外力超過0.03 時，力跟伸長將成線性關係，即外力將佔主導地位而熵效應較小。因此若要考慮熵效應，在我們的模型中，外力的範圍要小於0.03。我們的結果顯示自發曲率越大，相對伸長的變化也越大。我們還發現由於熱擾動增加，因此溫度越高，需要越大的外力才能把高分子鏈拉直。我們也考慮了排斥體積效應，並與未考慮排斥體積效應的結果做比較。我們發現在外力比較小的時候，考慮排斥體積效應後，高分子鏈的端點距離會比未考慮排斥體積效應來得大，但平均形狀差異不大。另外，溫度升高，亦使端點距離增大。但在我們所考慮的參數範圍內，排斥體積效應對伸長之影響不超過2.5％，對端點距離之影響不超過13％。

關鍵字

彈性 ； 半柔軟的生物高分子 ； 計算機模擬

並列摘要

We study the elasticity of two-dimensional semiflexible biopolymers with constant spontaneous curvature. We find that the relation between external force and extension becomes linear in our model when the external force is greater than 0.03. In other words, the external force
dominates the elasticity in this case. So if we want to consider the entropy effect, the external force should be smaller than 0.03. Our result shows that the greater the spontaneous curvature, the larger the relative extension. We also find that due to increasing thermal fluctuation, at the higher temperature it requires larger external force to straighten the polymer chain. We also study the effect of excluded volume. We find that the effect of excluded volume tends to enlarge the end-to-end distance
and extension when the external force is small, but it has little effect on the average shape. Moreover, the end-to-end distance also increases with increasing temperature. But within the range of parameter we considered,
the effect of excluded volume is smaller than 2.5% for extension, and smaller than 13% for end-to-end distance.

並列關鍵字

elasticity ； semiflexible biopolymers ； computer simulation.

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