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08:03
Study of Protein Dynamics via Neutron Spin Echo Spectroscopy
Published on: April 13, 2022
Increasing IgG concentration modulates the conformational heterogeneity and bonding network that influence solution
Tim J Kamerzell1, Sonoko Kanai, Jun Liu
1Department of Late Stage Pharmaceutical and Processing Development, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA. tkamer@gene.com
The Journal of Physical Chemistry. B
|April 4, 2009
Summary
High protein concentrations reveal unique molecular interactions. Increased hydrogen bonding and electrostatics drive immunoglobulin (IgG) association and viscosity changes, impacting protein behavior in solution.
Area of Science:
- Biochemistry
- Protein Chemistry
- Spectroscopy
Background:
- Protein stability, association, and recognition are influenced by molecular interactions in concentrated solutions.
- Understanding nonideal solution behavior is crucial for protein formulation and drug development.
Purpose of the Study:
- To investigate the molecular interactions modulating the nonideal solution behavior of immunoglobulins (IgG1s) at high concentrations.
- To identify the specific interactions responsible for increased viscosity and association in immunoglobulin solutions.
Main Methods:
- Two-dimensional vibrational correlation spectroscopy (2D-COS) was employed to analyze concentration-dependent spectral changes.
- Principal components analysis (PCA) was used to interpret complex spectral data and identify key variations.
- Vibrational spectra, particularly the amide II region, were analyzed to probe secondary structure and residue-specific interactions.
Main Results:
- A unique sequence of spectral changes deviating from ideality was observed in highly viscous immunoglobulin G solutions.
- Asynchronous spectra indicated that changes in beta-sheet and turn regions preceded alterations in disordered and alpha-helical regions with increasing concentration.
- Analysis of the amide II region suggested that glutamic acid (Glu) and aspartic acid (Asp) residues initiate increased viscosity and association.
Conclusions:
- Increased hydrogen bonding and electrostatic interactions are primary drivers of intermolecular association and nonideal behavior in concentrated immunoglobulin solutions.
- Specific amino acid residues, notably Glu and Asp, play a critical role in triggering concentration-dependent changes in immunoglobulin solution properties.
- The findings provide insights into the molecular mechanisms governing protein behavior at high concentrations, relevant for biopharmaceutical development.
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