title: Microscopic insight into role of protein flexibility during ion exchange chromatography by nuclear magnetic resonance and quartz crystal microbalance approaches.
abstract: Driven by the prevalent use of ion exchange chromatography (IEC) for polishing therapeutic proteins, many rules have been formulated to summarize the different dependencies between chromatographic data and various operational parameters of interest based on statically determined interactions. However, the effects of the unfolding of protein structures and conformational stability are not as well understood. This study focuses on how the flexibility of proteins perturbs retention behavior at the molecular scale using microscopic characterization approaches, including hydrogen-deuterium (H/D) exchange detected by NMR and a quartz crystal microbalance (QCM). The results showed that a series of chromatographic retention parameters depended significantly on the adiabatic compressibility and structural flexibility of the protein. That is, softer proteins with higher flexibility tended to have longer retention times and stronger affinities on SP Sepharose adsorbents. Tracing the underlying molecular mechanism using NMR and QCM indicated that an easily unfolded flexible protein with a more compact adsorption layer might contribute to the longer retention time on adsorbents. The use of NMR and QCM provided a previously unreported approach for elucidating the effect of protein structural flexibility on binding in IEC systems.
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Dongxia
authors.initials: D
authors.lastname: Hao
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Ge
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Yongdong
authors.initials: Y
authors.lastname: Huang
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Zhao
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China. Electronic address: ghma@ipe.ac.cn.
authors.forename: Guanghui
authors.initials: G
authors.lastname: Ma
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China. Electronic address: zgsu@ipe.ac.cn.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Su
mesh_terms: D000327:Adsorption; D002852:Chromatography, Ion Exchange; D003903:Deuterium; D009682:Magnetic Resonance Spectroscopy; D011506:Proteins / Q000737:chemistry*; D058525:Quartz Crystal Microbalance Techniques
chemical_list: D011506:Proteins; D003903:Deuterium
keywords: IEC; NMR; Protein structural flexibility; QCM; Retention time