Immunoglobulin Dynamics, Conformational Fluctuations, and Nonlinear Elasticity and Their Effects on Stability
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- 作者：Tim J. Kamerzell ; Joshua D. Ramsey ; C. Russell Middaugh
- 刊名：Journal of Physical Chemistry B
- 出版年：2008
- 出版时间：March 13, 2008
- 年：2008
- 卷：112
- 期：10
- 页码：3240 - 3250
- 全文大小：250K
- 年卷期：v.112,no.10(March 13, 2008)
- ISSN：1520-5207
文摘
The relationships between protein dynamics, function, and stability are incompletely understood. Two externalperturbations (temperature and pH) were used to modulate the flexibility and stability of an IgG1
monoclonalantibody (mAb) in an attempt to better understand the possible correlations between flexibility and stability.Ultrasonic velocimetry, densitometry, differential scanning calorimetry (DSC), and pressure perturbationcalorimetry (PPC) were used to experimentally determine the adiabatic and isothermal compressibility,expansibility, fractional volumes of unfolding, and various nonlinear thermoacoustical parameters as a functionof pH and temperature. By combining these results, state parameter fluctuations were calculated fromfundamental statistical mechanical relationships. The most dynamic and rigid mAb ensemble is measured atpH 4 and 6, respectively, based on state parameter fluctuations and compressibility. The effect of pH appearsto couple mAb dynamics to solvent fluctuations, which control its dynamics and stability. A nonlinear responseto mechanical perturbation, comparable to that seen with many polymers, is observed for this monoclonalantibody at pH 4-8. This behavior is characterized as strongly anisotropic and anharmonic, especially at pH4. The midpoint of thermal unfolding as measured by DSC does not necessarily correlate with flexibility.
monoclonalantibody (mAb) in an attempt to better understand the possible correlations between flexibility and stability.Ultrasonic velocimetry, densitometry, differential scanning calorimetry (DSC), and pressure perturbationcalorimetry (PPC) were used to experimentally determine the adiabatic and isothermal compressibility,expansibility, fractional volumes of unfolding, and various nonlinear thermoacoustical parameters as a functionof pH and temperature. By combining these results, state parameter fluctuations were calculated fromfundamental statistical mechanical relationships. The most dynamic and rigid mAb ensemble is measured atpH 4 and 6, respectively, based on state parameter fluctuations and compressibility. The effect of pH appearsto couple mAb dynamics to solvent fluctuations, which control its dynamics and stability. A nonlinear responseto mechanical perturbation, comparable to that seen with many polymers, is observed for this monoclonalantibody at pH 4-8. This behavior is characterized as strongly anisotropic and anharmonic, especially at pH4. The midpoint of thermal unfolding as measured by DSC does not necessarily correlate with flexibility.