Description
Streptavidin magnetic beads
GeniePure CA-28 Streptavidin Beads are streptavidin-coated magnetic beads for high-capacity capture and isolation of biotinylated nucleic acids, proteins and other biotin-tagged molecules. The strong streptavidin-biotin interaction enables efficient pull-down, target enrichment and washing in a magnetic format.
The beads are hydrophilic superparamagnetic polystyrene microspheres covalently coated with highly purified streptavidin, with a free biotin-binding capacity of >950 pmol/mg. The high affinity of the streptavidin-biotin interaction (Kd = 10-15 mol/L) gives fast, efficient binding of biotinylated nucleic acids, antibodies and other ligands. Uniform particle size and regular morphology give good repeatability and lot-to-lot stability. Applications include capture of target nucleic acid fragments with biotinylated probes (such as liquid hybridisation capture), immunoassays and nucleic acid-protein interaction studies. For research use only.
Key Features
| Hybridisation capture ready | Suitable for liquid hybridisation capture experiments. | |
| Efficient biotin binding | 1 mg (100 μl) of beads binds >950 pmol free biotin, or about 10 μg biotinylated dsDNA or 10 μg biotinylated IgG. | |
| Low nonspecific binding | Less than 1% of non-biotinylated nucleic acid is bound. | |
| Easy handling | Low-adsorption beads do not stick to tube walls. |
Specifications
| Bead type | Hydrophilic superparamagnetic polystyrene microspheres, covalently coated with streptavidin |
| Concentration | 10 mg/ml in PBST (pH 7.4) with 0.005% ProClin 300 |
| Free biotin-binding capacity | >950 pmol/mg |
| Binding capacity (per 1 mg) | About 10 μg biotinylated dsDNA or 10 μg biotinylated IgG |
| Nonspecific nucleic acid binding | <1% |
| Applications | Hybridisation capture, immunoassays, nucleic acid-protein interaction studies |
| Shelf life | 2 years |
Components
| Components | Amount |
| GeniePure CA-28 Streptavidin Beads* | 2.5 ml / 10 ml |
* 10 mg/ml in PBST (pH 7.4) containing 0.005% ProClin 300.
Storage
Store at 2 ~ 8°C.
This is a general procedure. Optimise the salt concentration and pH of the buffers for your samples.
Recommended binding and washing buffers (self-prepared)
| Buffer | Composition |
| 2× B&W Buffer (for biotinylated nucleic acid) | 10 mM Tris-HCl (pH 7.5), 1 mM EDTA, 2 M NaCl, 0.1% Tween 20 |
| PBST Buffer (for biotinylated antibody/protein) | PBS (pH 7.4), 0.05% Tween 20 |
To make 1× B&W Buffer, mix 1 volume of 2× B&W Buffer with 1 volume of nuclease-free ddH2O.
- Aliquot the beads
- Vortex the beads for 30 sec to resuspend. Transfer 100 μl to a 1.5 ml tube or 8-tube strip, place on a magnetic rack for 1 min and remove the supernatant.
- Calculate the bead amount from the biotinylated nucleic acid or protein content of the sample: 1 mg (100 μl) of beads binds about 10 μg biotinylated dsDNA or IgG.
- Wash the beads
- Off the rack, resuspend the beads in 1× B&W Buffer (nucleic acid) or PBST Buffer (protein) equal to the initial bead volume. Mix by pipetting gently 10 times or vortexing for about 10 sec.
- Centrifuge briefly, place on the rack for 1 min and remove the supernatant. Repeat once.
- Bind the biotinylated sample
- Resuspend the beads in 50 μl 2× B&W Buffer (nucleic acid) or PBST Buffer (protein), then add 50 μl biotinylated sample (make up to 50 μl with nuclease-free ddH2O if needed). Mix by pipetting 10 times or vortexing for about 10 sec.
- Incubate on a vertical rotating mixer at room temperature for 15–30 min (20–30 rpm recommended).
- Centrifuge briefly, place on the rack for 1 min and transfer the supernatant to a new tube for later use.
- Adjust the binding volume to the sample volume and concentration, keeping binding buffer to sample at 1:1. Bound nucleic acid or protein can be calculated by measuring the concentration before and after binding.
- Wash after binding
- Resuspend the beads in 1× B&W Buffer or PBST Buffer equal to the initial bead volume, mix by pipetting 10 times or vortexing for about 10 sec, centrifuge briefly, place on the rack for 1 min and remove the supernatant. Repeat once.
- Resuspend for downstream use
- Resuspend the beads in a low-salt buffer suitable for your downstream application.
Q1: How many beads do I need?
- 1 mg (100 μl) of beads binds >950 pmol free biotin, or about 10 μg biotinylated dsDNA or 10 μg biotinylated IgG. Calculate the bead volume from the amount of biotinylated material in your sample.
Q2: Which buffer should I use for binding?
- Use B&W Buffer (10 mM Tris-HCl pH 7.5, 1 mM EDTA, 2 M NaCl, 0.1% Tween 20 at 2×) for biotinylated nucleic acids, and PBST (PBS pH 7.4, 0.05% Tween 20) for biotinylated antibodies or proteins. Keep the binding buffer to sample ratio at 1:1.
Q3: What should I do if beads stick to the tube wall?
- In high-salt solutions, add 0.01%–0.05% Tween 20 to the solution in advance. Also use low-binding pipette tips and avoid high-speed centrifugation.
