ISBN 9783843948876

978-3-8439-4887-6, Reihe Thermodynamik

Hoang Tam Do
Melting Properties and Solubility of Amino Acids and Peptides

244 Seiten, Dissertation Technische Universität Dortmund (2021), Softcover, A5

Zusammenfassung / Abstract

Amino Acids and peptides are substance classes in the biochemical industry. The final products are often synthesized by fermentation and purified in a complex downstream process, where the crystallization is still used as the state-of-the-art separation step for which the knowledge about the solubility of every single solute is mandatory. Since the determination of experimental temperature-dependent solubility data is time-consuming and cost-intensive, modeling solubility using physical properties such as melting properties is highly desired. Unfortunately, the direct determination of melting properties for amino acids and peptides using conventional DSC is not possible due to the decomposition before their melting at low heating rates. This was overcome by applying Fast Scanning Calorimetry (FSC) with heating rates up to 20,000 K s-1 to measure the melting properties of 20 proteinogenic amino acids and 22 peptides with a focus on isomeric dipeptides and tripeptides based on glycine, L-alanine, L-leucine, L-proline and L-serine. The experimental FSC-measured melting properties were used as input data in the thermodynamic modeling framework PC-SAFT to model the solubility in water and in water + 2-propanol solutions. Furthermore, three gE models (Wilson, NRTL, UNIQUAC) were applied to model solubility. The experimental determination of solubility in water and in water + 2-propanol solutions was performed using photometric method and the gravimetric method of supersaturated solutions. Additionally, the pH-value and the crystal structure were investigated to ensure the neutral species in solution and to exclude crystal structure changes in the solid phase. In summary, the synergy between FSC and PC-SAFT opens the door for solubility modeling of biomolecules that decompose before their melting.