Proteomics Applications of Magnetic Silica Beads

Topics Covered

Magsi Proteomics Reversed Phase Magnetic Beads (C4, C8, C18)
     MagSi-Proteomics Order Information
MagSi-WCX
     MagSi-WCX order information
MagSi-WAX
     MagSi-WAX order information
MagSi-custom
About AMSBIO

Magsi Proteomics Reversed Phase Magnetic Beads (C4, C8, C18)

MagSi-proteomics beads are magnetic beads that are an ideal tool for the purification, concentration and desalting of peptides and protein digests. The surface of the beads has been modified with C4, C8 and C18 -alkyl groups that are typical for reversed phase applications.

MagSi proteomics reversed phase beads have several advantages:

  • Magnetic beads can be easily used in automated liquid handling platform in high throughput mode
  • Enhances significantly the throughput over widely used tip based solutions
  • Compared to Zip Tips™, the MagSi proteomics beads are up to 3 times more cost effective

The MagSi proteomics beads have been demonstrated as powerful tool in desalting of proteomics sample after protein digestion and prior to mass spectrometry (Figure 1):

Figure 1. Spectra of peptides after elution with 30% acetonitrile. MagSi C18 beads show 23 annotated proteins (blue) as compared to the two reference beads, 7 (red) and 11 (green) respectively

MagSi proteomics products efficiently bind and elute even tiny sample fractions. Peptide amounts as low as 20 – 50 ng can be desalted by MagSi proteomics C8 and C18 beads and analyzed by state of the art MALDI-TOF instruments. The MagSi-proteomics C8 beads are designed for analysis of peptides and small proteins. An overview of some relevant spectra can be seen in figure 2a and b.

Figure 2a. Maldi Tof spectra in reflector mode analysing a peptide mix containing: Angiotensin (MW 1296); Neurotensin (MW 1673); ACTH Frag 1-17 (MW 2093); ACTH Frag 18 – 39 (MW 2465); ACTH Frag 7–38 (MW3657)

Figure 2b. MALDI-TOF spectra in linear mode representing the protein myoglobin.

Typically for small peptides MagSi-proteomics C8 or C18 beads are suited best, whereas MagSi proteomics C4 and the MagSi-WCX are well suited for larger proteins. Table 1 outlines the typical size regions :

Table 1. Bead selection table linking bead type to Molecular Weight of target (Da)

Please note: The table above is a guideline based on size. The net charge and hydophobicity are further characteristics to be considered to choose the right MagSi magnetic bead in your proteomic application. Please email amsbio for support (info@amsbio.com).

In general it can be stated that the MagSi proteomics beads become more hydrophobic the longer the alkyl chains are. Therefore the MagSi-proteomics C8 beads represent the intermediate bead type of choice in context to proteomic profiling and biomarker research. The relatively low hydrophobicity of the C4 beads allows the purification and fractionation of larger bio-molecules like proteins. MagSi-proteomics C18 is on the other end of the spectrum most suitable for peptide analysis.

MagSi-Proteomics Order Information

MagSi magnetic silica particles with modified C4, C8 or C18 surface

Art. Nr.

Product

Conc.

Size

Volume

MD01014

MagSi-proteomics C4

10mg/ml

1.2μm

2ml

MD02014

MagSi-proteomics C4

10mg/ml

1.2μm

10ml

MD01015

MagSi-proteomics C8

10mg/ml

1.2μm

2 ml

MD02015

MagSi-proteomics C8

10mg/ml

1.2μm

10 ml

MD01009

MagSi-proteomics C18

10mg/ml

1.2μm

2ml

MD03009

MagSi-proteomics C18

10mg/ml

1.2μm

10ml

MagSi-WCX

The MagSi-WCX (weak cation exchange) magnetic beads have the typical ion exchange properties well known from classical chromatography. Protein and peptides are charged at the surface and will be adsorbed to magnetic beads under low salt condition. Under high salt conditions or by pH shift the target proteins/peptides are eluted (ion exchanged).

Due to the different binding/elution mechanisms the MagSi-WCX beads are a powerful alternative to the MagSi proteomics beads. The MagSi-WCX magnetic beads fit very well, when you expect many proteins at neutral pI values. If you expect more analytes with acidic pI we recommend to consider also the MagSi-WAX beads (below).

MagSi-WCX beads are magnetic silica beads with a high magnetic content optimized for protein and peptide separation. Furthermore they are ideally suited for typical proteomics applications like desalting procedures. Especially in clinical proteomics samples (e.g tissue samples) they are the bead of choice.

Fig. 3 shows a reference spectra for a standard protein mix used for MALDI-TOF calibration.

Figure 3. MALDI-TOF spectra in linear mode for a analysis of a protein calibration mix containing BSA, Myoglobin, Aldolase and Enolase.

MagSi-WCX order information

MagSi magnetic silica particles with weak cation exchange surface (WCX)

Art. Nr.

Product

Conc.

Size

Volume

MD01023

MagSi-WCX

20mg/ml

1.2μm

2ml

MD04023

MagSi-WCX

20mg/ml

1.2μm

20ml

MagSi-WAX

The MagSi-WAX (weak anion exchange) magnetic beads are the “counter” beads to the MagSi WCX beads. Binding, washing and elution are also triggered by the protein/peptide total net charge. The MagSi-WAX beads are ideally suited when more acidic proteins/peptides are expected in the sample. However, our protocols given in the corresponding product sheet cover buffer systems for acidic, neutral and basic conditions.

MagSi-WCX beads are magnetic silica beads with a high magnetic content optimized for protein and peptide separation. Since the MagSi-WCX and MagSi-WAX act as counter-beads, we recommend to test both types of beads, to see which suits best in your individual application.

MagSi-WAX order information

MagSi magnetic silica particles with weak anion exchange surface (WAX)

Art. Nr.

Product

Conc.

Size

Volume

MD01025

MagSi-WCX

20mg/ml

1.2μm

2ml

MD04025

MagSi-WCX

20mg/ml

1.2μm

20ml

MagSi-custom

Our dedicated team of chemists, biologists and biomarker experts can be your sparring partner in selecting the right bead for your intended application, or can help to customize bead-chemistry to your demand and the biomarker’s specifications. Fig. 4 shows many, but not all possibilities, we have to develop your specific bead for your specific biomarker application.

Figure 4. MagCustom toolbox. Quantum dots (green) or fluorescent dyes (red) and any other molecules (?) can be encapsulated next to the FerroFluids (black). On the surface different biomolecules like antibodies, proteins, streptavidin (STA), protein A or G and other biological and non- biological molecules can be attached on demand.

About AMSBIO

AMSBIO’s mission is to be a profitable premier provider of quality life science research reagents and services helping customers develop innovative methods, processes, products and medicines.

This is achieved by offering small and medium size manufacturers, academic groups and revenue generating biotechs a unique partnership for the global market and by providing state of the art and cost effective solutions to end users and partners.

Source: AMSBIO.

For more information on this source, please visit AMSBIO.

 

Date Added: May 17, 2013 | Updated: Jun 11, 2013
Ask A Question

Do you have a question you'd like to ask regarding this article?

Leave your feedback
Submit