Surface Activated Dynabeads.indd - Invitrogen

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A variety of ways to bind your ligand
Manual or automated handling
Protein separation technology
Introduction
Dynabeads ® are superparamagnetic monosized polymer
spheres. They are magnetic only when placed in a magnetic
field, with no magnetic remanence when the magnetic field
is removed. Dynabeads ® are composed of highly cross-linked
polystyrene with magnetic material precipitated in evenly
distributed pores. The ferrous compound is sealed inside the
bead by an additional layer of polymer. Chemical groups are
then introduced onto the bead surface to facilitate binding
of almost any ligand, and subsequent easy and convenient
isolation of the bound target (fig. 1).
Unique Monodispersity
The unique monodispersity and uniformity
of the Dynabeads ® provide optimal and
reproducible reaction kinetics, and a rapid
and efficient binding of target molecules.
Dynabeads ® are easily dispersed and
handle almost like a liquid. In addition,
chemical agglutination and nonspecific
binding are negligible as
compared with irregularly shaped
particles.
Hydrophobic or
Hydrophilic
Dynal Biotech provides surface
activated Dynabeads ® with
both hydrophobic and hydrophilic
characteristics:
The hydrophilic beads allow
for gentle coupling of ligands
to the surface. The functional
ac tivit y of enz y mes and
labile proteins is therefore
intact after immobilisation.
T he hydrophilic proper ties
of the beads ensure optimal
dispersion in suspension. Very
low nonspecific binding of proteins,
dyes etc. is observed with the pH
neutral M-270 Epoxy beads, thus
the requirement for blocking agents
is reduced. The functional groups of
the M-270 Amine and Carboxylic Acid
beads allow further introduction of a large
variety of alternative reactive groups by using
commercially available cross-linkers.
Fig. 1 Principle of biomagnetic
separation with Dynabeads ® .
Surface Activated Dynabeads ®
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Superior reproducibility
All-in-one-tube protocols
Easy handling and no sample loss
A hydrophobic surface is an excellent choice for coupling of
antibodies for affinity purification of organelles or proteins.
The hydrophobic Fc region of the antibody is adsorbed to the
hydrophobic bead surface, followed by a rapid covalent bond
formation. The orientation of the antibody is optimal, with the
Fab regions facing outwards. The resultant yield of target protein
or organelle fractionation is elevated.
Small or Large, Automation or Manual Handling
Dynal Biotech offers surface activated Dynabeads ® of various
sizes. For work with proteins, nucleic acids or similar materials,
we recommend the 1.0 µm (the MyOne TM series) or the 2.8 µm
(the M-280 and M-270 series). The larger 4.5 µm beads are well
suited to isolating larger entities such as organelles or cells.
Due to their size and high iron content they exert a strong pull
to the magnet, even in viscous samples, yet still retain gentle
handling of the bound target. The Dynabeads ® are easy to
handle manually using simple magnet racks for the isolation
of target.
Dynabeads ® MyOne TM are ideal for isolation of smaller entities
such as proteins and bacteriophages. In addition, the 1.0
µm beads have a large surface area, high capacity, efficient
magnetic pull and excellent properties for automation. The
MyOne TM products are tailor-made for use in automated
protocols where high throughput is crucial. Dynal Biotech
has developed suitable protocols for several of the robotic
workstations available on the market.
Specific Considerations
To obtain the best possible result, it is important to choose the
correct product for your specific application. The table on page
5 will help you decide which product to use. The choice will first
of all depend on the nature of the ligand.
A successful coupling of a ligand to tosylactivated beads
requires primary amino- or sulphydryl groups. The orientation
of the active site of the ligand must also be taken into
consideration. Hydrophobic beads facilitate interactions
between the beads and the hydrophobic parts of the proteins,
whereas the hydrophilic beads are suitable when interactions
between the beads and the hydrophilic parts of the proteins
are desired. If the ligand is a labile peptide or protein, the best
choice is to use beads with epoxy groups allowing for coupling
down to 4°C. Carboxylic acid beads, with which peptide bonds
are formed within minutes, are a satisfactory alternative.
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