摘要翻译：
我们考虑了在其环境中大小为M的一般不可压缩有限模型蛋白，我们用一个半柔性共聚物来表示它，该共聚物由氨基酸残基组成，在Lau和Dill之后只分为两种（H和P,见正文）。我们允许在给定序列中化学上未键合的残基与溶剂（水）之间的各种相互作用，并精确地列举了在两种不同条件下无限晶格上作为能量E的函数的构象数W(E)：(i)我们允许被限制为紧致的构象（称为Hamilton walk构象）和(ii)我们允许无限制的构象，也可以是非紧致的。尽管我们的模型在热力学极限下呈现出一个剧烈的折叠跃迁，但我们很容易用合理的论据证明它不具有任何能隙。这个计数使我们能够准确地研究能量学对自然态的影响，以及小尺寸对蛋白质热力学的影响，特别是对微正则系综和正则系综之间差异的影响。我们发现有限系统的正则熵比微正则熵大得多。我们研究了自平均的性质，并得出小蛋白质不自平均的结论。我们还提供了(i)对能量景观的一些理解，(ii)对不同温度下的自由能景观有所启发的结果。
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英文标题：
《Exact Statistical Mechanical Investigation of a Finite Model Protein in
  its environment: A Small System Paradigm》
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作者：
P. D. Gujrati, Bradley P. Lambeth Jr, Andrea Corsi and Evan Askanazi
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最新提交年份：
2007
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分类信息：

一级分类：Physics        物理学
二级分类：Statistical Mechanics        统计力学
分类描述：Phase transitions, thermodynamics, field theory, non-equilibrium phenomena, renormalization group and scaling, integrable models, turbulence
相变，热力学，场论，非平衡现象，重整化群和标度，可积模型，湍流
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一级分类：Quantitative Biology        数量生物学
二级分类：Biomolecules        生物分子
分类描述：DNA, RNA, proteins, lipids, etc.; molecular structures and folding kinetics; molecular interactions; single-molecule manipulation.
DNA、RNA、蛋白质、脂类等；分子结构与折叠动力学；分子相互作用；单分子操作。
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英文摘要：
  We consider a general incompressible finite model protein of size M in its environment, which we represent by a semiflexible copolymer consisting of amino acid residues classified into only two species (H and P, see text) following Lau and Dill. We allow various interactions between chemically unbonded residues in a given sequence and the solvent (water), and exactly enumerate the number of conformations W(E) as a function of the energy E on an infinite lattice under two different conditions: (i) we allow conformations that are restricted to be compact (known as Hamilton walk conformations), and (ii) we allow unrestricted conformations that can also be non-compact. It is easily demonstrated using plausible arguments that our model does not possess any energy gap even though it is supposed to exhibit a sharp folding transition in the thermodynamic limit. The enumeration allows us to investigate exactly the effects of energetics on the native state(s), and the effect of small size on protein thermodynamics and, in particular, on the differences between the microcanonical and canonical ensembles. We find that the canonical entropy is much larger than the microcanonical entropy for finite systems. We investigate the property of self-averaging and conclude that small proteins do not self-average. We also present results that (i) provide some understanding of the energy landscape, and (ii) shed light on the free energy landscape at different temperatures.
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PDF链接：
https://arxiv.org/pdf/708.3739