Melting Properties of Peptides and Their Solubility in Water. Part 2: Di- and Tripeptides Based on Glycine, Alanine, Leucine, Proline, and Serine
Melting Properties of Peptides and Their Solubility in Water. Part 2: Di- and Tripeptides Based on Glycine, Alanine, Leucine, Proline, and Serine
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DOI：
10.1021/acs.iecr.0c05652
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发表时间：
2021-02-08
影响因子：
4.2
通讯作者：
Held, Christoph
中科院分区：
文献类型：
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作者：
Hoang Tam Do;Chua, Yeong Zen;Held, Christoph
在肽的下游工艺中，结晶仍然被用作最先进的分离步骤，其中必须了解每种单一化合物的溶解度。由于确定与温度相关的实验溶解度数据既耗时又昂贵，因此非常需要基于物理特性（例如熔融特性）对溶解度进行建模。不幸的是，由于肽在熔化之前会分解，所以使用传统的差示扫描量热法直接测定生物分子的熔化特性是不可能的。在这项工作中，采用加热速率高达 20,000 K s(-1) 的快速扫描量热法 (FSC) 测量了 22 种肽的熔解特性，重点关注基于甘氨酸、L-丙氨酸、L-亮氨酸、L-脯氨酸和 L-丝氨酸的异构二肽和三肽。使用光度法（紫外/可见光谱仪）和过饱和溶液的重量法对这些肽的水溶性进行实验测定。此外，还测定了肽的pH值和晶体结构，以确保溶液中的中性物质并排除固相中的晶体结构变化。实验 FSC 测量的熔化特性被用作热力学建模框架 PC-SAFT 中的输入数据，以模拟肽在水中的溶解度。肽的 PC-SAFT 纯组分参数是按照本工作中引入的加权联合参数方法确定的。这种方法允许通过连接母体氨基酸的纯组分参数来确定肽的纯组分参数。肽和水之间的二元相互作用参数适合与溶解度无关的特性，例如肽水溶液的渗透系数和混合物密度。模拟的肽溶解度与实验溶解度非常吻合。
In downstream processes for peptides, crystallization is still used as the state-of-the-art separation step for which the knowledge about the solubility of each single compound is mandatory. Since the determination of experimental temperature-dependent solubility data is time-consuming and expensive, modeling solubility based on physical properties such as melting properties is highly desired. Unfortunately, the direct determination of melting properties for biomolecules using conventional differential scanning calorimetry is not possible due to the decomposition of the peptides before their melting. In this work, fast scanning calorimetry (FSC) with heating rates up to 20,000 K s(-1) was applied to measure the melting properties of 22 peptides with focus on isomeric dipeptides and tripeptides based on glycine, L-alanine, L-leucine, L-proline, and L-serine. The experimental determination of the aqueous solubility of these peptides was performed using the photometric method (UV/Vis spectrometer) and the gravimetric method of supersaturated solutions. Additionally, the pH value and the crystal structure of peptides were determined in order to ensure the neutral species in solution and to exclude crystal structure changes in the solid phase. The experimental FSC-measured melting properties were used as input data in the thermodynamic modeling framework PC-SAFT to model the peptide solubility in water. The PC-SAFT pure-component parameters of the peptides were determined following a weighted joint-parameter method introduced in this work. This approach allows determining the pure-component parameters of a peptide by joining the pure-component parameters of the parent amino acids. The binary interactions parameter between peptide and water was fitted to solubility-independent properties such as osmotic coefficients and mixture densities of aqueous peptide solutions. The modeled peptide solubility was in good agreement with the experimental solubility.