Thermodynamic and Fluorescence Analyses to Determine Mechanisms of IgG1 Stabilization and Destabilization by Arginine
ABSTRACT Purpose To investigate mechanisms governing the stabilization and destabilization of immunoglobulin (IgG1) by arginine (Arg). Methods The effects of Arg on the aggregation/degradation, thermodynamic stability, hydrophobicity, and aromatic residues of IgG1 were respectively investigated by s...
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Veröffentlicht in: | Pharmaceutical research 2014-04, Vol.31 (4), p.992-1001 |
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Sprache: | eng |
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Zusammenfassung: | ABSTRACT
Purpose
To investigate mechanisms governing the stabilization and destabilization of immunoglobulin (IgG1) by arginine (Arg).
Methods
The effects of Arg on the aggregation/degradation, thermodynamic stability, hydrophobicity, and aromatic residues of IgG1 were respectively investigated by size-exclusion chromatography, differential scanning calorimetry, probe fluorescence, and intrinsic fluorescence.
Results
Arg monohydrochloride (Arg–HCl) suppressed IgG1 aggregation at near-neutral pH, but facilitated aggregation and degradation at acidic pH or at high storage temperature. Equimolar mixtures of Arg and aspartic acid (Asp) or glutamic acid (Glu) suppressed aggregation without facilitating degradation even at high temperature. Arg–HCl decreased the thermodynamic stability of IgG1 by enthalpic loss, which was counteracted by using Asp or Glu as a counterion for Arg. The suppression of aggregation by Arg–HCl was well correlated with the decrease in hydrophobicity of IgG1. The intrinsic fluorescence of IgG1 was unaffected by Arg–HCl.
Conclusions
Suppression of IgG1 aggregation can be attributed to the interaction between Arg and hydrophobic residues; on the other hand, facilitation of aggregation and degradation is presumably due to the interaction between Arg and some acidic residues, which could be competitively inhibited by simultaneously adding either Asp or Glu. |
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ISSN: | 0724-8741 1573-904X |
DOI: | 10.1007/s11095-013-1221-2 |