Applications of zeolite inorganic composites in biotechnology: current state and perspectives.
ABSTRACT The purpose of this short review is to introduce applications of inorganic composites, zeolites, in biotechnology. Although inorganic chemistry is generally considered distant from biotechnology, the two could be harmoniously integrated for biopolymer chromatography. New chromatographic carriers have been developed based on principles differing from those underlying conventional chromatography. Some can be used for the purification of proteins according to novel physicochemical principles, according to their isoelectric point (pI), molecular weight and shape. The amount of protein adsorbed is related to the pore size of the composites, which can recognize biomolecules with reference to these three parameters. Proteins adsorbed at their pI have been found to be desorbed at the pI by polyethylene glycol, but not by high ionic medium (NaCl), SDS, non-ionic detergents, ATP or urea. Therefore, inorganic composites synthesized in consideration of pore size and three-dimensional structure are suitable as new chromatographic carriers. Selective fractionation of biomaterials including proteins and nucleic acids should provide useful information regarding whether conjugated proteins in a precipitated state can be separated on net charge and whether cells can be directly fractionated in future.
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ABSTRACT: Hydrophobic zeolite Y can be used as a fast and efficient and inexpensive matrix in the purification of proteins from crude extracts. Preferably the zeolite can be used in the first purification step, replacing the commonly used precipitation techniques with (NH4)2SO4 or ethanol. The time required for the zeolite prefractionation was a few hours compared to the much more time consuming precipitation procedure which demands centrifugation and subsequent dialysis. Proteins can be absorbed on the zeolite either in order to remove undesired proteins or to be subsequently eluted from the zeolite in order to achieve purification and concentration. Removal of undesired proteins is exemplified by the purification of horseradish peroxidase from a crude extract. The zeolite procedure enhanced the specific activity five times and provided a yield similar to that which was obtained by the use of standard procedures, (NH4)2SO4 fractionation and ion-exchange chromatography. Binding and subsequent elution of proteins from the zeolite is exemplified by the purification of monoclonal antibodies from hybridoma culture supernatants. Proteins were desorbed from the zeolite by the use of polyethylene glycol 600 and this procedure yielded a purification factor of 5.Protein Expression and Purification 01/1995; 5(6):569-76. · 1.43 Impact Factor
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ABSTRACT: The adsorption of proteins on ultrastable zeolites was investigated. Protein binding to one of these, ultrastable zeolite Y (USY), was studied in detail. Protein binding to USY, with a Si/Al ratio of > 240, was found to be dependent on the pH of the solution, being highest at or just below the pI of the protein. The amount of protein adsorbed on the zeolite was found to be 10 times as much as the estimated binding to the external surface of the USY. We propose an adsorption mechanism involving the formation of a protein layer strongly bound to the USY surface, further protein layers being formed on top of this on the basis of protein-protein interactions. The protein-protein interactions can be disrupted by changing the pH. Ultrastable zeolite Y was used as a new matrix for protein purification. Undesired proteins can be removed from a crude preparation by adsorption on USY, increasing the purity of a specific protein, or the protein can be adsorbed on the zeolite and subsequently eluted through changing the pH. These two means of protein purification are exemplified by the purification of peroxidase from a crude horseradish extract and by the purification of lysozyme from egg white.Protein Expression and Purification 07/1997; 10(2):247-55. · 1.43 Impact Factor
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ABSTRACT: The adsorption of macromolecules on zeolite crystal surfaces has been investigated by cryo transmission electron microscopy (TEM) of frozen hydrates. It was determined that ferritin shows different adsorption behavior on NaY (TEM image on the right) and USY zeolites (TEM image on the left).Angewandte Chemie International Edition 10/1999; 38(17):2560-2562. · 13.73 Impact Factor