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Chromatographic HPV‐16 E6/E7 plasmid vaccine purification employing L‐histidine and 1‐benzyl‐L‐histidine affinity ligands
Author(s) -
Amorim Lúcia F. A.,
Gaspar Rita,
Pereira Patrícia,
Černigoj Urh,
Sousa Fani,
Queiroz João António,
Sousa Ângela
Publication year - 2017
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201700147
Subject(s) - histidine , chemistry , nucleic acid , elution , ligand (biochemistry) , chromatography , selectivity , dna , amino acid , catalysis , organic chemistry , biochemistry , receptor
Abstract Affinity chromatography based on amino acids as interacting ligands was already indicated as an alternative compared to ion exchange or hydrophobic interaction for plasmid DNA purification. Understanding the recognition mechanisms occurring between histidine‐based ligands and nucleic acids enables more efficient purification of a DNA vaccine, as the binding and elution conditions can be adjusted in order to enhance the purification performance. Decreasing pH to slightly acidic conditions increases the positive charge of histidine ligand, what influences the type of interaction between chromatographic support and analytes. This was proven in this work, where hydrophobic effects established in the presence of ammonium sulfate were affected at pH 5.0 in comparison to pH 8.0, while electrostatic and cation‐π interactions were intensified. Histidine ligand at pH 5.0 interacts with phosphate groups or aromatic rings of plasmid DNA. Due to different responses of RNA and pDNA on mobile phase changes, the elution order between RNA and pDNA was changed with mobile phase pH decrease from 8.0 to 5.0. The phenomenon was more evident with L‐histidine ligand due to more hydrophilic character, leading to an improved selectivity of L‐histidine‐modified chromatographic monolith, allowing the product recovery with 99% of purity (RNA removal). With the 1‐benzyl‐ L‐histidine ligand, stronger and less selective interactions with the nucleic acids were observed due to the additional hydrophobicity associated with the phenyl aromatic ring. Optimization of sample displacement chromatography parameters (especially (NH 4 ) 2 SO 4 concentration) at slightly acidic pH enabled excellent isolation of pDNA, by the removal of RNA in a negative mode, with binding capacities above 1.5 mg pDNA per mL of chromatographic support.