Thiol-Activated Peptide Conjugation Magnetic Beads

$480.00  $320.00
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Faster Magnetic Response; Simpler Protocols;

LifeTein’s unique coupling chemistry enables fast and efficient covalent conjugation of amino (-NH2) and thiol (-SH) containing proteins and peptides, to the solid core with iron oxide clusters. All steps in the coupling are performed at physiological conditions and at room temperature with high yields and short reaction times. The magnetic product consists of nano-superparamagnetic beads, which are functionalized with high-density maleimide groups. The beads are used to couple thiol-containing ligands such as peptides, proteins, antibodies, and aptamers. Subsequently, target proteins are easily separated from the solution using a magnet for downstream experiments. 

The magnetic beads show superior magnetic behavior and are easily attracted to external magnets allowing separation within seconds. The matrix enables minimal nonspecific binding of proteins due to its hydrophilic nature. The beads are black and easily observed by the eye and dense, making them easy to spot and collect. The beads do not aggregate and are easily re-suspended in most buffers.

The coupling capacity is general 1-10 mg protein or 0.1-1mg peptide/ml beads.

The number of beads needed can easily be scaled up or down to match antibody concentration and sample volumes. The beads are suitable for separations from the ul to 500 ml scale using appropriate magnetic separators.

Magnetic bead
Catalog Number:
Packing Details:
20mg in N, N-dimethylacetamide (DMAC)

The magnet is not provided.

Binding Capacity:
1-10 mg protein or 0.1-1mg peptide/mg maleimide magnetic beads.
Particle size:
500nm diameter
Coupling conditions:
Tris buffer , pH 7.2 containing 5mM TCEP (tris(2-carboxyethyl)phosphine)
Coupling capacity:
1-10 mg protein or 1 mg peptide/mg beads.

Coupling capacity was determined by incubating 30mg beads with human lgG (1 mg/ml in 1ml PBS) for 60 minutes at room temperature.

Product shipped at room temp. Upon receipt, please store at 2-8°C.
Shelf Life:
Stable for at least two years
Recommended Buffers:

Solvent: N, N-dimethylacetamide (DMAC)

Washing Solution: Tris buffer, pH 7.2 

Coupling Solution: Tris buffer, pH 7.2 containing 5mM TCEP

Blocking Solution: Tris buffer, pH 7.2 containing 100ug/ml L-cysteine



Sample Preparation

1. Dissolve 1-10mg protein/peptide in 0.5-1ml coupling buffer. Protein concentration is typically 1-10mg/ml. 

2. If samples have already suspended in other buffers, dilute samples with an equal volume of coupling buffer.

Protein Coupling

1. Gently mix the magnetic beads thoroughly before use by shaking.

2. Place 1 mg of magnetic beads into a microcentrifuge tube.

3. Place the tube into a magnetic stand, collect the beads, and discard the supernatant.

4. Wash the beads three times with Washing Solution (1 ml each time) by magnetic separation, and re-suspend the beads in 0.5 ml of Coupling Solution.

5. Add 0.5 ml of the protein solution to 0.5 ml of the bead suspension; mix thoroughly and incubate for 4-16 hrs at 4°C on a rotator.

6. Add 2 ml of Blocking Solution. Mix thoroughly and incubate overnight at 4 °C on a rotator.

7. Collect the beads with a magnet and save the supernatant for analysis if needed.

8. Wash the protein-coupled beads twice with Washing Solution (1 ml each time) by magnetic separation.

9. Suspend the beads with the desired volume of Washing Solution or in a buffer compatible with the attached protein. Store at 4°C until ready for use.

Important Notes

1. Maleimides react with free sulfhydryl groups at a pH 6.5-7.5, forming stable, covalent thioether bonds. At pH > 7.5, maleimide reacts with amine groups. Therefore, accurate pH measurement is necessary when preparing solutions used in the experiment.

2. The reduction of disulfide bonds in the protein is needed before coupling. A 10-fold molar excess of a reducing agent such as DTT or TCEP is sufficient. If DTT is used, dialysis is required to remove excess DTT before the coupling step. However, the removal of TCEP is not needed.

3. EDTA can be included in the coupling buffer to chelate stray divalent metals that otherwise promote oxidation of non- reactive sulfhydryls.

4. Protein and bead concentrations should be optimized. Too low a protein concentration may result in bead crosslinking.

5. Do not freeze, dry, or centrifuge at high speed during the use or storage of beads. Otherwise, this may decrease the binding capacity of the beads.

The product is not thoroughly tested and is not intended for human use. For in-vitro and research use only.

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