Protein formulation through automated screening of pH and buffer conditions, using the Robotein® high throughput facility

Investigating the effect of solvent polarity environment differences in electrolyte and non-electrolyte systems

To address the knowledge gap regarding the polarity of excipient solutions and the impact on biologically relevant systems, a comprehensive exploration of the polarity of solutions is essential. This study explores the solvatochromic response of Reichardt's dye to solvent polarity in aqueous solutions, focusing on structurally similar electrolytes and non-electrolytes at concentrations typically used in pharmaceutical formulations. UV absorbance measurements demonstrated sensitivity to subtle structural differences, such as counterion variations or glycosidic bonds. Here, chloride salts and disaccharides were analyzed and notable polarity differences between similar systems were found. Additionally, unexpected similarities between sodium chloride and trehalose were observed. This investigation underscores the potential of readily accessible solvent polarity and solvatochromic studies to deepen the understanding of aqueous solutions and extend their application to pharmaceutical excipients and their roles in protein formulation.

Development of a fluorescence-based excipient screening for improved stability and shelf-life of recombinant chitin deacetylase

Chitin deacetylase (CDA) modifies chitin into chitosan by removing acetyl groups, but its inherent instability poses a challenge for successful crystallisation. Despite limited successes in crystallizing CDAs, prior attempts with recombinant chitin deacetylase (BaCDA) failed due to poor stability. To address this, we propose an enzyme buffer formulation as a cost-effective strategy to enhance stability, prolong shelf life, and increase the likelihood of crystallisation. Utilizing the high-throughput screening technique FTSA, we developed a screening method correlating BaCDA stability with its activity. The optimised formulation comprises 50 mM Tris-HCl buffer pH 7, 1 M NaCl, 20 % glycerol, and 1 mM Mg2+ as excipients. This formulation significantly improves BaCDA's thermostability (140.47 % increase) and enzyme activity (2.9-fold enhancement). BaCDA remains stable in the formulated buffer at -20 °C and -80 °C for 30 days and at 4 °C for 15 days. The current study has designed a high-throughput screening method approach to assess the stability of CDA enzyme formulations. The results of this study could contribute to the exploration of formulation elements that enhance the structural stability of CDA, thereby facilitating investigations into the enzyme's structure-function relationships.