indirect methods described in the section on cell separation (Sect. 2.1.1) are
equally valid for macromolecules as well. Although both the direct and indirect
methods perform well, the direct method is generally more controllable.
However, the indirect method may perform better for antibodies with poor
affinity or when antigen is rare or less accessible [33].
Many magnetic adsorbents have been used for the isolation of various biologically active macromolecules such as enzymes, enzyme inhibitors, DNA,
RNA, antibodies, antigens, etc. from different sources such as nutrient media,
fermentation broth, tissue extracts, body fluids, and others. However, the
present discussion is restricted to enzymes only.
In the case of enzymes, an appropriate affinity ligand is usually immobilized
on a magnetic carrier such as silanized magnetite or on polymeric magnetic
(chitin) or magnetizable particles. Alternatively, it is possible to begin with a
standard affinity chromatography gel and to modify it magnetically by passing
ferrofluid through the gel column [117]. Examples of magnetically assisted
separation of enzymes are shown in Table 3.
3.2.2
Electro-Extraction
As both the phases of ATPSs are electrically conductive, application of electric
fields in these systems gives rise to electrokinetic mass transfer of charged
species. Thus ATPS was shown as a medium for electrophoretic separation with
two aqueous phase interfaces providing the stability against convection and
facilitating product recovery [126]. Proteins have been directed into either the
174
K.S.M.S. Raghavarao et al.
Table 3. Magnetically assisted separation of enzymes
Enzyme
Magnetic system
Reference
ADH, LDH, 6-PGDH
Ferrofluid-modified 5¢-AMP-sephadex 4B
[117]
Hexokinase, G-6-PDH
Magnetic aqueous two-phase system ADH, PTK
[118]
Asparaginase
Magnetic polyacrylamide gel with immobilized
[119]
d-asparagine
b-Galactosidase
Silanized magnetite with immobilized
[119]
p-aminophenyl-b-d-thiogalactopyranoside
Chymostrypsin
Chitosan-magnetic beads
[120]
G-6-PDH
Ferrofluid-modified 2¢,5¢-ADP-Sepharose 4B
[121]
LDH
Magnetic agarose with immobilized triazine dye
[122]
Lysozyme
Magnetic chitin
[123]
Pectinase
Alginate-magnetite beads
[124]
Trypsin
Magnetic polyurethane-polystyrene beads with
[125]
immobilized soy trypsin inhibitor
Trypsin
Sub-micron ferrite particles with immobilized
[29]
soybean trypsin inhibitor
equally valid for macromolecules as well. Although both the direct and indirect
methods perform well, the direct method is generally more controllable.
However, the indirect method may perform better for antibodies with poor
affinity or when antigen is rare or less accessible [33].
Many magnetic adsorbents have been used for the isolation of various biologically active macromolecules such as enzymes, enzyme inhibitors, DNA,
RNA, antibodies, antigens, etc. from different sources such as nutrient media,
fermentation broth, tissue extracts, body fluids, and others. However, the
present discussion is restricted to enzymes only.
In the case of enzymes, an appropriate affinity ligand is usually immobilized
on a magnetic carrier such as silanized magnetite or on polymeric magnetic
(chitin) or magnetizable particles. Alternatively, it is possible to begin with a
standard affinity chromatography gel and to modify it magnetically by passing
ferrofluid through the gel column [117]. Examples of magnetically assisted
separation of enzymes are shown in Table 3.
3.2.2
Electro-Extraction
As both the phases of ATPSs are electrically conductive, application of electric
fields in these systems gives rise to electrokinetic mass transfer of charged
species. Thus ATPS was shown as a medium for electrophoretic separation with
two aqueous phase interfaces providing the stability against convection and
facilitating product recovery [126]. Proteins have been directed into either the
174
K.S.M.S. Raghavarao et al.
Table 3. Magnetically assisted separation of enzymes
Enzyme
Magnetic system
Reference
ADH, LDH, 6-PGDH
Ferrofluid-modified 5¢-AMP-sephadex 4B
[117]
Hexokinase, G-6-PDH
Magnetic aqueous two-phase system ADH, PTK
[118]
Asparaginase
Magnetic polyacrylamide gel with immobilized
[119]
d-asparagine
b-Galactosidase
Silanized magnetite with immobilized
[119]
p-aminophenyl-b-d-thiogalactopyranoside
Chymostrypsin
Chitosan-magnetic beads
[120]
G-6-PDH
Ferrofluid-modified 2¢,5¢-ADP-Sepharose 4B
[121]
LDH
Magnetic agarose with immobilized triazine dye
[122]
Lysozyme
Magnetic chitin
[123]
Pectinase
Alginate-magnetite beads
[124]
Trypsin
Magnetic polyurethane-polystyrene beads with
[125]
immobilized soy trypsin inhibitor
Trypsin
Sub-micron ferrite particles with immobilized
[29]
soybean trypsin inhibitor