Relationship between human IgG structure and retention time in hydroxyapatite chromatography with sodium-phosphate gradient elution

Retention Mechanism of Proteins in Hydroxyapatite Chromatography - Multimodal Interaction Based Protein Separations: A Model Study

BACKGROUND

Retention mechanism of proteins in hydroxyapatite chromatography (HAC) was investigated by linear gradient elution experiments (LGE).

MATERIALS AND METHODS

Several mobile phase (buffer) solution strategies and solutes were evaluated in order to probe the relative contributions of two adsorption sites of hydroxyapatite (HA) particles, C-site due to Ca (metal affinity) and P-site due to PO4 (cation-exchange). When P-site was blocked, two basic proteins, lysozyme (Lys) and ribonuclease A(RNase), were not retained whereas cytochrome C(Cyt C) and lactoferrin (LF) were retained and also retention of acidic proteins became stronger as the repulsion due to P-site was eliminated. The number of the binding site B values determined from LGE also increased, which also showed reduction of repulsion forces.

CONCLUSION

The selectivity (retention) of four basic proteins (RNase, Lys, Cyt C, LF) in HAC was different from that in ion-exchange chromatography. Moreover, it was possible to tune the selectivity by using NaCl gradient.

Monoclonal antibody purification by ceramic hydroxyapatite chromatography

Hydroxyapatite chromatography is shown to be an excellent method for chromatographically purifying monoclonal antibodies (Mab). Mab contained in eluates from Protein A columns was partially purified on ceramic hydroxyapatite (CHT™) Type I, 40 μm ceramic hydroxyapatite using two scouting methods which provide milligram amounts of Mab typical at laboratory scale. The result from one of the scouting methods was optimized to obtain a high concentration of purified Mab with acceptable clearance of cell culture impurities. Several techniques (linear phosphate screening, linear alkaline salt screening, and two alkaline salt step gradients) are described for obtaining high concentrations of purified Mab in a lab-scale CHT chromatography column.

Facile synthesis of hydroxyapatite nanoparticles, nanowires and hollow nano-structured microspheres using similar structured hard-precursors

A facile strategy was developed to delicately control the morphologies of hydroxyapatite materials from simple 0D morphologies to complicated 3D architectures using hard-precursors with similar structures. The present study provides a new platform for hydroxyapatite materials to be efficiently synthesized and manipulated.