Chemical Modification Alters Protein–Protein Interactions and Can Lead to Lower Protein Solubility

Abstract

The chemical modification of proteins is at the frontier of developments in biological imaging and biopharmaceutics. With the advent of more sensitive and higher resolution imaging techniques, researchers increasingly rely on the functionalization of proteins to enable these techniques to capture cellular processes. For biopharmaceutical therapies, chemically modified proteins, for example, antibody-drug conjugates (ADCs) offer the possibility of more tailored treatments for the disease with lower toxicities than traditional small molecule therapies. However, relatively little consideration is paid to how chemical modifications impact protein−protein interactions and solution stability. Using human γD-crystallin as a model, we demonstrate that chemical modification of the protein surface alters protein−protein interactions, which can result in lower solubility depending on the chemical nature of the modifier and the position on the protein where the modification is made. Understanding these effects is essential to ensure that modifying proteins effectively occurs with minimum selfassociation and that studies carried out using labeled proteins accurately reflect those of unmodified proteins.

Alteration of Physicochemical Properties for Antibody-Drug Conjugates and Their Impact on Stability

“…82 The ability of proteins to stay in solution is often described as solubility even though proteins, unlike chemical compounds, do not fulfill the criteria; proteins rather form colloidal and nonideal solutions. 83 The maximal capacity of such a colloidal solution depends on several physicochemical properties such as hydrophobicity 84 or their consequence such as self-interaction, 85 which is of highest importance for high-concentration protein formulations. Poor capacity of the colloidal solution often translates into increased aggregate and particle formation or precipitation at higher protein concentrations.…”

Protein–polymer mixtures in the colloid limit: Aggregation, sedimentation, and crystallization

“…Finally, salts can also affect the hydrophobic protein-protein interactions by increasing the surface tension. 85 These interactions have shown to be relevant in the formation of a crystal phase and protein solubility, 115,116 which cannot be discarded in the present study.…”

Protein-Polymer Mixtures in the Colloid Limit: Aggregation, Sedimentation and Crystallization

“…Finally, salts can also affect the hydrophobic protein-protein interactions by increasing the surface tension. 86 These interactions have shown to be relevant in the formation of a crystal phase and protein solubility, 112,113 which cannot be discarded in the present study.…”