Materials Research Laboratory, University of Nova Gorica, Vipavska 13, SI-5000, Nova Gorica, Slovenia.
Materials Research Laboratory, University of Nova Gorica, Vipavska 13, SI-5000, Nova Gorica, Slovenia.
Arch Biochem Biophys. 2024 Oct;760:110132. doi: 10.1016/j.abb.2024.110132. Epub 2024 Aug 23.
Differential Scanning Calorimetry (DSC) is a regular and powerful tool to measure the specific heat profile of various materials. Hydrogen bonds play a crucial role in stabilizing the three-dimensional structure of proteins. Naturally, information about the strength of hydrogen bonds is contained in the measured DSC profiles. Despite its obvious importance, there is no approach that would allow the extraction of such information from the heat capacity measurements. In order to connect the measured profile to microscopic properties of a polypeptide chain, a proper model is required to fit. Using recent advances in the Zimm-Bragg (ZB) theory of protein folding in water, we propose a new and efficient algorithm to process the DSC experimental data and to extract the H-bonding energy among other relevant constants. Thus, for the randomly picked set of 33 proteins, we have found a quite narrow distribution of hydrogen bonding energies from 1 to 8 kJ/mol with the average energy of intra-protein hydrogen bonds h¯=4.2±1.5 kJ/mol and the average energy of water-protein bonds as h¯=3.8±1.5 kJ/mol. This is an important illustration of a tiny disbalance between the water-protein and intraprotein hydrogen bonds. Fitted values of the nucleation parameter σ belong to the range from 0.001 to 0.01, as expected. The reported method can be considered as complementary to the classical two-state approach and together with other parameters provides the protein-water and intraprotein H-bonding energies, not accessible within the two-state paradigm.
差示扫描量热法（DSC）是一种常规且强大的工具，可用于测量各种材料的比热曲线。氢键在稳定蛋白质的三维结构中起着至关重要的作用。自然地，关于氢键强度的信息包含在测量的 DSC 曲线中。尽管其重要性显而易见，但目前还没有一种方法可以从热容测量中提取出这些信息。为了将测量的曲线与多肽链的微观性质联系起来，需要一个合适的模型来拟合。利用最近在水相蛋白质折叠的 Zimm-Bragg（ZB）理论方面的进展，我们提出了一种新的、高效的算法来处理 DSC 实验数据，并提取氢键能等相关常数。因此，对于随机挑选的 33 种蛋白质，我们发现氢键能的分布相当狭窄，范围在 1 到 8 kJ/mol 之间，平均内蛋白氢键能 h¯为 4.2±1.5 kJ/mol，平均水-蛋白键能 h¯为 3.8±1.5 kJ/mol。这是水-蛋白和内蛋白氢键之间微小失衡的重要例证。如预期的那样，成核参数 σ 的拟合值属于 0.001 到 0.01 的范围。所报道的方法可以被认为是对经典二态方法的补充，并且与其他参数一起提供了蛋白质-水和内蛋白氢键能，这些信息在二态范式中是无法获得的。
