Advances in protein solubility and thermodynamics: quantification, instrumentation, and perspectives

Abstract

While protein crystallization has broadly been applied to determine the 3D structure of proteins, it has recently drawn great attention to replace the traditional downstream processing for protein-based biopharmaceuticals due to its advantages in stability, storage, and delivery. However, establishing the crystallization conditions of a protein remains a challenge because of the limited understanding of the underlying phenomena. This highlight provides a critical review of the advanced experimental approaches to measure thermodynamic parameters (e.g. solubility) that can help in establishing the necessary conditions to perform a protein crystallization trial. Firstly, methods and techniques to assess protein crystallizability and solution quality are presented. Next, methodologies to measure the main thermodynamic parameters are revised (with the respective advantages, limitations, and studied proteins). Later, protocols and set-ups (with a focus on microfluidic devices) used to quantify solubility parameters are highlighted (involved apparatus capabilities, solubility screening details, and studied proteins). Lastly, future directions and outlook of this critical review are approached by covering new trends in the research field.