Folding and other protein self-assembly processes are driven by favorable interactions between O, N, and C unified atoms of the polypeptide backbone and sidechains. These processes are perturbed by solutes that interact with these atoms differently than water does. C=O · · · HN hydrogen bonding and various π-system interactions have been better-characterized structurally or by simulations than experimentally in water, and unfavorable interactions are relatively uncharacterized. To address this situation, we previously quantified interactions of alkylureas with amide and aromatic compounds, relative to interactions with water. Analysis yielded strengths of interaction of each alkylurea with unit areas of different hybridization states of unified O, N, C atoms of amide and aromatic compounds. Here, by osmometry, we quantify interactions of ten pairs of amides selected to complete this dataset. A novel analysis yields intrinsic strengths of six favorable and four unfavorable atom-atom interactions, expressed per unit area of each atom and relative to interactions with water. The most favorable interactions are sp²O - sp²C (lone pair-π, presumably n-π*), sp²C - sp²C (π-π and/or hydrophobic), sp²O-sp²N (hydrogen bonding) and sp³C-sp²C (CH-π and/or hydrophobic). Interactions of sp³C with itself (hydrophobic) and with sp²N are modestly favorable, while sp²N interactions with sp²N and with amide/aromatic sp²C are modestly unfavorable. Amide sp²O-sp²O interactions and sp²O-sp³C interactions are more unfavorable, indicating the preference of amide sp²O to interact with water. These intrinsic interaction strengths are used to predict interactions of amides with proteins and chemical effects of amides (including urea, N-ethylpyrrolidone (NEP), and polyvinyl-pyrrolidone (PVP)) on protein stability.

中文翻译：

---

实验确定的负责蛋白质自组装在水中的原子-原子（C，N，O）相互作用的强度：在折叠和其他蛋白质工艺中的应用

折叠和其他蛋白质自组装过程是由多肽主链和侧链的O，N和C统一原子之间的有利相互作用驱动的。与水不同，与这些原子相互作用的溶质会扰乱这些过程。C = O···HN氢键和各种π系统相互作用的结构或模拟结果均比水中的实验结果更好，不利的相互作用则相对较不特征。为了解决这种情况，我们先前定量了相对于与水的相互作用，烷基脲与酰胺和芳族化合物的相互作用。分析产生了每个烷基脲与酰胺和芳族化合物的统一O，N，C原子的不同杂交状态的不同单位面积的相互作用强度。在这里，通过渗透压 我们量化选择十对酰胺以完成此数据集的相互作用。一项新颖的分析得出了六种有利和四种不利的原子-原子相互作用的内在强度，这些强度分别表示为每个原子的单位面积以及相对于与水的相互作用。最有利的互动是sp² O-sp ² C（孤对-π，大概为n-π*），sp ² C-sp ² C（π-π和/或疏水性），sp ² O-sp ² N（氢键）和sp ³ C-sp ² C（CH-π和/或疏水性）。SP的相互作用³与自身（疏水性），并用SPÇ ² N为温和有利，而SP ^2间n，其中SP相互作用² N和具有酰胺/芳族SP ² C是适度不利的。酰胺sp ² O-sp ² O相互作用和sp ² O-sp ³C的相互作用更不利，表明酰胺sp ² O优选与水相互作用。这些固有的相互作用强度可用于预测酰胺与蛋白质的相互作用以及酰胺（包括尿素，N-乙基吡咯烷酮（NEP）和聚乙烯吡咯烷酮（PVP））对蛋白质稳定性的化学作用。