Understanding the Stabilizing Effect of Histidine on mAb Aggregation: A Molecular Dynamics Study

Area of Science:

• Biochemistry
• Pharmaceutical Sciences
• Computational Biology

Background:

• Histidine is a common buffer in monoclonal antibody (mAb) formulations, known to reduce protein aggregation.
• The precise microscopic mechanism of histidine's stabilizing effect on mAbs remains elusive.
• Existing research suggests the effect is neither electrostatic nor related to secondary structure preservation.

Purpose of the Study:

• To elucidate the molecular-level interactions between histidine buffer and mAbs.
• To understand the mechanism underlying histidine's ability to prevent antibody aggregation.
• To inform the prediction of histidine's efficacy in various therapeutic formulations.

Main Methods:

• All-atom molecular dynamics simulations were employed to model histidine-mAb interactions.
• Contact-based free energy calculations were utilized to quantify these interactions.
• The Spatial Aggregation Propensity index was reformulated to incorporate buffer-protein interactions.

Main Results:

• Histidine buffer molecules adsorb onto the mAb surface.
• This adsorption reduces the exposure of hydrophobic protein regions to the solvent.
• The study identified shielding of hydrophobic areas as the key stabilizing mechanism.

Conclusions:

• Histidine stabilizes mAb formulations by physically shielding solvent-exposed hydrophobic regions.
• This mechanism explains the observed reduction in antibody aggregation.
• Understanding this interaction is crucial for optimizing therapeutic protein formulations.