表面活化的Dynabeads磁珠提供哪些活性基团？
我们提供甲苯磺酰基、环氧基、羧基和胺基活化的Dynabeads磁珠。请点击链接（https://tools.thermofisher.com/content/sfs/brochures/Surface_Activated_Dynabeads.PDF）查看不同磁珠的对比信息。
What reactive groups do you offer for your surface-activated Dynabeads magnetic beads?
We offer tosyl, epoxy, carboxylic acid and amine activated Dynabeads magnetic beads. Please see the link (https://tools.thermofisher.com/content/sfs/brochures/Surface_Activated_Dynabeads.PDF) for a comparison of the beads.
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
What is the density of Dynabeads magnetic beads?
The density of Dynabeads magnetic beads is a challenging property to determine. The reason is that Dynabeads magnetic beads have a 17-37% magnetic iron oxide content in order to have a reasonable magnetic separation time, and the density of the iron oxide is about 4.9 g/cm3. Dynabeads magnetic beads are composite materials, being a mix of polymers and iron oxide, and there are very few polymers that have a density below 1.
The sedimentation rate depends on the bead diameter squared, so the sedimentation of a 1 µm bead is much slower than that of 2.8 µm. The effect of diameter on sedimentation rate is to some extent counteracted by the fact that smaller beads need to have a higher content of iron oxide for magnetic separation applications. Typically, our M-280 Dynabeads (diameter 2.8 µm) have a density of 1.4 g DS/cm3 (DS = dry substance), our M-270 Dynabeads (diameter 2.8 µm) and M-450 Dynabeads (diameter 4.5 µm) have a density of 1.6 g DS/cm3, and our MyOne Dynabeads (diameter 1 µm) have a density of 1.8 g DS/cm3.
Find additional tips, troubleshooting help, and resources within our Dynabeads Nucleic Acid Purification Support Center as well as our Dynabeads Cell Isolation and Expansion Support Center and Protein Immunoprecipitation (IP), Co-Immunoprecipitation (Co-IP), and Pulldown Support Center.
I am using surface-activated Dynabeads magnetic beads. When do I need to use a linker secondary antibody?
A linker antibody provides proper orientation of the target-specific primary antibody. Optimal orientation of the primary antibody is more important for reacting with larger organelles than for small organelles or membrane fractions. Different linkers can be used, but we recommend using an Fc-binding antibody, such as a monoclonal or polyclonal anti-mouse IgG. The linker antibody must be affinity purified and not contain stabilizers such as sugars or proteins that may bind to the Dynabeads magnetic beads. The specific primary antibody, if polyclonal, must be affinity purified in order to provide a high density of the specific antibody on the Dynabeads magentic beads surface.
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
Which surface-activated Dynabeads magnetic beads should I choose for immobilizing my protein?
This depends on the nature of the specific ligand to be immobilized and the desired downstream application.
-The most frequently used surface-activated Dynabeads magnetic beads for protein isolation are the Tosyl-activated Dynabeads magnetic beads M-280. These beads are hydrophobic, easy to handle and ideal for covalent binding of antibodies for immunoprecipitation. Other ligands could also be covalently bound to these beads, but they have to tolerate conditions like neutral to high pH and high temperatures (required for covalent bond formation).
-Dynabeads magnetic beads M-270 Epoxy are used when the ligand to be immobilized needs to be treated gently and will not tolerate harsh binding conditions like high temperature or pH. Proteins/peptides (other than antibodies) and enzymes are often coupled onto these beads.
-Dynabeads magnetic beads M-270 Amine is often used in combination with crosslinkers to create specific surface groups on the beads. Hetro-bifunctional crosslinkers with an amine-reactive NHS group at one end and another chemical group of your choice at the other end are most frequently used. For example, Dynabeads magnetic beads M-270 Amine can be reacted with a hetero-bifunctional crosslinker containing a NHS group at one end and maleimide at the other end to create Dynabeads magnetic beads with a maleimide surface. Since maleimide reacts specifically with sulfhydryl groups, these modified Dynabeads magnetic beads can be used for applications where binding of sulfhydryl groups are desired. Dynabeads magnetic beads M-270 Amine may also be used for direct ligand coupling via aldehyde or ketone groups by Schiff base (imine) formation and reductive amination. In addition carboxylic acid groups on a ligand can be activated with a carbodiimide like EDC, which results in a direct amide bond formation between the beads and the ligand. Alternatively, a crosslinker may be introduced to the ligand. After activation of the ligand with crosslinker, the free end on the crosslinker has to be amine reactive.
-Dynabeads magnetic beads M-270 Carboxylic Acid and Dynabeads magnetic beads MyOne Carboxylic Acid can also be used for immobilizing proteins. The carboxylic acid groups on these beads need to be activated with a carbodiimide before coupling. The negatively-charged surface of these beads may attract positively charged proteins and cause nonspecific binding. This needs to be considered if these beads are going to be used for immunoprecipitation.
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
