A monoclonal antibody fragment (Fab) undergoes reversible gelation when incubated at temperatures greater than 30°C at high protein concentration (&gt; 100 mg/mL) and pH &lt; 5.5.  This behavior appears to be facilitated by isomerization (Asu formation) of a solvent accessible aspartic acid residue.  The extent of gelation during incubation at high temperature, as monitored by turbidity and viscosity, was found to correlate with Asu levels, as monitored by ion exchange chromatography (IEC).  The rate of gelation was also found to decrease with increasing solution ionic strength, indicating that electrostatic interactions are involved in the gelation mechanism.  Changes in the biophysical properties of the protein were observed via circular dichroism (CD), intrinsic Trp fluorescence, and differential scanning calorimetry (DSC) during the gelation process, indicating that Asp isomerization could be inducing a loss in tertiary structure.  To further investigate the relationship between Asp isomerization and gelation behavior, a mutant with the labile Asp residue substituted was evaluated and found to improve the physical properties of the protein. <br/>

Investigating a correlation between chemical degradation and gelation behavior observed for a monoclonal Fab

255th National Meeting (2018)

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