Search Merck Eurolab Ltd Hydroxy apatite for Biochromatography Hydroxy apatite is an inorganic chromatography material, in contrast to most ion exchange supports that are based on organic matrices. It is a useful tool for purification of proteins, enzymes, monoclonal antibodies and nucleic acids. Hydroxy apatite is often used to remove nucleic acids from pharmaceutical products and for separation of isoenzymes.
Hydroxy apatite consists of calcium phosphate, thus containing positive and negative charges.
Hydroxy apatite chromatography should be performed within a pH-range from 6 to 9 to obtain the zwitterionic state of a given protein. Even though the binding mechanism is not completely understood, ionic interactions as well as adsorption effects seem to contribute to protein binding. This means that the distribution of charges within the biomolecule affects binding significantly. Experiments have shown that acidic proteins mainly bind to calcium ions whereas basic proteins mainly bind to phosphate groups. Some proteins can also be bound in the presence of high concentration of sodium chloride.