title: Conformational and Colloidal Stabilities of Human Immunoglobulin G Fc and Its Cyclized Variant: Independent and Compensatory Participation of Domains in Aggregation of Multidomain Proteins.
abstract: Monoclonal immunoglobulin G (IgG) is a multidomain protein. It has been reported that the conformational and colloidal stabilities of each domain are different, and it is predicted that limited domains participate in IgG aggregation. In contrast, the influence of interdomain interactions on IgG aggregation remains unclear. The fragment crystallizable (Fc) region is also a multidomain protein consisting of two sets of CH2 and CH3 domains. Here, we have analyzed the conformational change and aggregate size of an aglycosylated Fc region induced by both acid and salt stresses and have elucidated the influence of interdomain interactions between CH2 and CH3 domains on the conformational and colloidal stabilities of the aglycosylated Fc region. Singular value decomposition analyses demonstrated that the CH2 and CH3 domains unfolded almost independently from each other in the aglycosylated Fc region. Meanwhile, the colloidal stabilities of the CH2 and CH3 domains affect the aggregation process of the unfolded aglycosylated Fc region in a compensatory way. Moreover, the influence of an additional interdomain disulfide bond, introduced at the C-terminal end of the CH3 domains to produce the Fc variant, cyclized Fc, was evaluated. This interdomain disulfide bond increased the conformational stability of the CH3 domain. The stabilization of the CH3 domain in the cyclized Fc successfully improved aggregation tolerance following acid stress, although the sizes of aggregates produced were comparable to those of the aglycosylated Fc region.
authors.affiliation: Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.|Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology , AIST Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Seiki
authors.initials: S
authors.lastname: Yageta
authors.affiliation: Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Risa
authors.initials: R
authors.lastname: Shibuya
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology , AIST Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Hiroshi
authors.identifier: 0000-0001-8924-747X
authors.initials: H
authors.lastname: Imamura
authors.affiliation: Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.|Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology , AIST Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Shinya
authors.identifier: 0000-0002-7878-3944
authors.initials: S
authors.lastname: Honda
mesh_terms: D002942:Circular Dichroism; D003500:Cyclization / Q000502:physiology; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry*; D007074:Immunoglobulin G / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D013312:Stress, Physiological / Q000502:physiology
chemical_list: D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G
keywords: acid stress; aggregation; antibody; multidomain; unfolding