title: Assessment of the Protein-Protein Interactions in a Highly Concentrated Antibody Solution by Using Raman Spectroscopy.
abstract: OBJECTIVE
  To investigate the protein-protein interactions of a highly concentrated antibody solution that could cause oligomerization or aggregation and to develop a better understanding of the optimization of drug formulations.
  
  
  METHODS
  In this study, we used Raman spectroscopy to investigate the structure and interactions of a highly concentrated antibody solution over a wide range of concentrations (10-200 mg/mL) with the aid of a multivariate analysis.
  
  
  RESULTS
  Our analysis of the amide I band, I 856 /I 830 of Tyr, and the relative intensity at 1004 cm(-1) of the Phe and OH stretching region at around 3000 cm(-1) showed that across this wide range of concentrations, the secondary structure of the IgG molecules did not change; however, short-range attractive interactions around the Tyr and Phe residues occurred as the distance between the IgG molecules decreased with increasing concentration. Analysis of the OH stretching region at around 3000 cm(-1) showed that these short-range attractive interactions correlated with the amount of hydrated water around the IgG molecules.
  
  
  CONCLUSIONS
  Our data show that Raman spectroscopy can provide valuable information of the protein-protein interactions based on conformational approaches to support conventional colloidal approaches, especially for analyses of highly concentrated solutions.
authors.affiliation: Advanced R&D Center, Horiba, Ltd., 2 Miyanohigashi, Kisshoin, Minami-ku, Kyoto, 601-8510, Japan. chikashi.ota@horiba.com.
authors.forename: Chikashi
authors.identifier: http://orcid.org/0000-0002-7547-1902
authors.initials: C
authors.lastname: Ota
authors.affiliation: Advanced R&D Center, Horiba, Ltd., 2 Miyanohigashi, Kisshoin, Minami-ku, Kyoto, 601-8510, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Noguchi
authors.affiliation: Department of Bioengineering, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Nagatoishi
authors.affiliation: Department of Bioengineering, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.|Laboratory of Medical Proteomics, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo, Japan.|Drug Discovery Initiative, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kouhei
authors.initials: K
authors.lastname: Tsumoto
mesh_terms: D000818:Animals; D007074:Immunoglobulin G / Q000737:chemistry*; D066329:Protein Aggregates; D011487:Protein Conformation; D055503:Protein Multimerization; D011817:Rabbits; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D007074:Immunoglobulin G; D066329:Protein Aggregates
keywords: Raman spectroscopy; antibody drug; biopharmaceutical; protein–protein interaction