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Small-Angle Neutron Scattering Study of a Monoclonal Antibody Using Free-Energy Constraints



Nicholas James Clark, Hailiang Zhang, Susan T. Krueger, Hyo Jin Lee, Randy R. Ketchem, Bruce Kerwin, Sekhar R. Kanapuram, Michael J. Treuheit, Arnold McAuley, Joseph E. Curtis


Monoclonal antibodies (mAbs) contain hinge-like regions of structural flexibility that enable the mobility of globular domains that have direct effect on biological function. A subclass of human mAbs, IgG2, has several inter-chain disulfide bonds in the hinge region that could potentially limit structural flexibility of the globular domains and therefore can affect the overall configuration space available to the mAb. We have studied a well characterized IgG2 mAb in solution via small angle neutron scattering (SANS) and interpreted the scattering data using atomistic models. Molecular Monte Carlo combined with molecular dynamics simulations of a model mAb indicate that a wide range of structural configurations are plausible spanning radius of gyration values from 39 to 56 A. Structural ensembles and representative single structure solutions were derived by comparison of theoretical SANS profiles of mAb models to experimental SANS data. Additionally, molecular mechanical and solvation free-energy calculations were carried out on the ensemble of best-fitting mAb structures. The results of this study indicate that low-resolution techniques like small-angle scattering combined with atomistic molecular simulations with free-energy analysis may be helpful to determine the types of intramolecular interactions that influence function and could lead to deleterious changes to mAb structure. This methodology will be useful to analyze small-angle scattering data of many macromolecular systems.
Journal of Physical Chemistry B


SANS, antibody, molecular dynamics, Monte Carlo, Modeling


Clark, N. , Zhang, H. , Krueger, S. , Lee, H. , Ketchem, R. , Kerwin, B. , Kanapuram, S. , Treuheit, M. , McAuley, A. and Curtis, J. (2013), Small-Angle Neutron Scattering Study of a Monoclonal Antibody Using Free-Energy Constraints, Journal of Physical Chemistry B, [online], (Accessed February 21, 2024)
Created October 10, 2013, Updated October 12, 2021