Technology

Protein A, G, A/G, and L

Protein A, G, A/G, and L are native and recombinant proteins whose antibody-binding properties have been well characterized. The native proteins are replaced by the recombinant proteins produced in E.coli since the recombinant proteins have higher capacity, are highly robust, and have maximum specific antibody binding. The characteristics of these recombinant proteins are summarized in table 1.

Protein A, Protein G, or Protein A/G binds with high affinity to the Fc portion of various classes and subclasses of immunoglobulins from various species by independent and separate binding sites. Protein L binds the different antibody isotypes (IgG, IgM, IgA, IgE, and IgD) through the interaction with the variable domain of the Ig kappa light chain with no interference with an antibody’s antigen-binding site. These proteins vary in their ability to bind to different subtypes and species antibodies. Therefore, choosing the antibody-binding proteins to match the corresponding antibody is essential. Refer to table 2 to select the antibody-binding protein that is best for your application.

Table 1. Characteristics of Protein A, Protein G, Protein A/G, Protein L

Protein A

Protein G

Protein A/G

Protein L

Original Source

Staphylococcus aureus

Staphyl-ococcus aureus

Streptococcus spp.
(Group C and G)

Strepto-coccus spp.
(Group C and G)

Staphylococcus aureus & Streptococcus spp.
(Group C and G)

Staphyl-ococcus aureus & Strepto-coccus spp.
(Group C and G)

Peptostreptococcus magnus

Peptostr-eptoco-ccus magnus

Recombinant Size (E.coli)

Recombi-nant Size (E.coli)

33 kDa

22 kDa

50 kDa

38 kDa

Number of Ig Binding Domains

Ig-binding site

Heavy chain constant region (Fc) of IgG
(CH2-CH3 region)

Kappa light chains of Igs
(VL-kappa)

Source

Antibody

Anti-body

Protein L

Protein A

Protein G

Protein A/G

Mouse

IgG 1

++++

+++

IgG 3

++++

IgG 2a

++++

IgG 2b

++++

IgM

++++

–

Total IgG

++++

Human

IgG 1

++++

IgG 2

++++

IgG 3

++++

IgG 4

++++

IgA

++++

–

IgD

++++

–

IgM

++++

–

Fab

++++

scFv

++++

–

Total IgG

++++

Rat

IgG 1

++++

+++

IgG 2a

++++

IgG 2b

++++

–

IgG 2c

++++

Total IgG

++++

+++

Sheep

IgG 1

–

++++

IgG 2

–

++++

Total IgG

–

++++

Horse

IgG (ab)

N/A

–

IgG (c)

N/A

–

IgM (T)

N/A

–

++++

Total IgG

N/A

++++

Goat

IgG 1

–

++++

IgG 2

–

++++

Total IgG

–

++++

Cow

IgG 1

–

++++

IgG 2

–

++++

Total IgG

–

++++

Rabbit

Total IgG

++++

Guinea Pig

Total IgG

N/A

++++

Pig

Total IgG

++++

Cat

Total IgG

N/A

++++

Dog

Total IgG

N/A

++++

Due to remarkable antibody binding characteristics, the proteins are widely used in antibody purification, immunoprecipitation (IP), chromatin immunoprecipitation (ChIP), immobilization or detection of immunoglobulins.

Bioclone develops a great antibody affinity chromatography matrix – Protein A, G, A/G, and L magnetic beads – used for antibody purification from serum, cell culture supernatant, or ascites, as well as antigen IP/Co-IP from cell or tissue extracts. The procedure for those Magnetic Beads has been improved to allow maximum recovery and purity of the recovered antibody or antigen. For antibody purification, the beads are incubated with the antibody solution, which is magnetically separated from the supernatant. For immunoprecipitation, the beads are delivered to an antigen-containing sample to which antibody has been introduced and allowed to incubate to form the antibody-antigen complex. The attached antibodies or antigens are dissociated from the beads using an elution buffer and recovered from the solution manually using a magnetic stand or by using automation instruments.

BcMag™ Protein A Magnetic Beads

The BcMag™ Protein A Magnetic Beads are high-capacity, high-throughput affinity particles used in antibody purification and immunoprecipitation procedures with manual or robotic magnetic separators. The magnetic microspheres are covalently immobilized with a high density ultrapure (Purity>97%) recombinant protein A proteins. Protein A Magnetic Beads are utilized for antibody purification from serum, cell culture supernatant, or ascites, and antigen IP/Co-IP from cell or tissue extracts. The Protein A Magnetic Beads procedure has been improved to allow maximum recovery and purity of the recovered antibody or antigen. For antibody purification, the beads are incubated with the antibody solution, which is magnetically separated from the supernatant. For immunoprecipitation, the beads are delivered to an antigen-containing sample to which antibody has been introduced and allowed to incubate to form the antibody-antigen complex. The attached antibodies or antigens are dissociated from the beads using an elution buffer and recovered from the solution manually using a magnetic stand or by using automation instruments.

Explore Products

Protein A Magnetic Beads Purification Kit

Protein A Europium Fluorescent Magnetic Beads

Protein A Terbium Fluorescent Magnetic Beads

Protein A Ruthenium Fluorescent Magnetic Beads

BcMag™ Protein G Magnetic Beads

BcMag™ Protein G Magnetic Beads are magnetic microspheres covalently immobilized with a high density ultrapure (Purity>97%) recombinant Protein G fusion protein. The beads are manufactured using nanometer-scale superparamagnetic iron oxide as core and entirely encapsulated by a high purity silica shell, ensuring no leaching problems with the iron oxide. Beads are specifically designed, tested, and quality controlled for immunoprecipitation and cell sorting when a selected primary antibody is used. Additionally, the beads are widely used for quick and efficient one-step purification of antibodies from Serum samples, ascites fluid, plasma, or tissue culture supernatant from several species.

Explore Products

Protein G Magnetic Beads Purification Kit

Protein G Europium Fluorescent Magnetic Beads

Protein G Terbium Fluorescent Magnetic Beads

Protein G Ruthenium Fluorescent Magnetic Beads

BcMag™ Protein A/G Magnetic Beads

BcMag™ Protein A/G Magnetic Beads are high-capacity, high-throughput affinity particles used in antibody purification and immunoprecipitation procedures with manual or robotic magnetic separators. The magnetic microspheres are covalently immobilized with a high density ultrapure (Purity>97%) recombinant protein A/G proteins. Protein A/G Magnetic Beads are utilized for antibody purification from serum, cell culture supernatant, or ascites, and antigen IP/Co-IP from cell or tissue extracts. The procedure for Protein A/G Magnetic Beads has been improved to allow maximum recovery and purity of the recovered antibody or antigen. For antibody purification, the beads are incubated with the antibody solution, after which they magnetically separated from the supernatant. For immunoprecipitation, the beads are added to an antigen-containing sample to which an antibody has been introduced and allowed to incubate to form the antibody-antigen complex. The attached antibodies or antigens are dissociated from the beads using an elution buffer and recovered from the solution manually using a magnetic stand or by using automation instruments.

Explore Products

Protein A/G Purification Kit

Protein A and G Europium Fluorescent Magnetic Beads

Protein A and G Terbium Fluorescent Magnetic Beads

Protein A and G Ruthenium Fluorescent Magnetic Beads

BcMag™ Protein L Magnetic Beads

BcMag™ Protein L Magnetic Beads are magnetic microspheres covalently immobilized with a high density ultrapure (Purity>95%) recombinant protein L. The beads are typically used for antibody isolation from serum, cell culture supernatant, ascites, immunoprecipitation, and co-immunoprecipitation of antigens from cell or tissue extracts. For antibody purification, the beads are incubated with the antibody solution, after which they magnetically separated from the supernatant. For immunoprecipitation, the beads catch the antigen-antibody complex from the sample. The attached antibodies and antigens are dissociated from the beads using an elution buffer and recovered from the solution manually using a magnetic stand or by using automation instruments.

Explore Products

Protein L Purification Kit

Protein L Europium Fluorescent Magnetic Beads

Protein L Terbium Fluorescent Magnetic Beads

Protein L-Ruthenium Fluorescent Magnetic Beads

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General Reference

L Björck, G Kronvall. (1984) Purification and some properties of streptococcal protein G, a novel IgG-binding reagent. The Journal of Immunology, Vol 133, Issue 2: 969-974

Björck L, et al. (1987) Streptococcal protein G, expressed by streptococci or by Escherichia coli, has separate binding sites for human albumin and IgG. Mol Immunol., 24(10): 1113-22

Eirini Kitsiouli, et al. (2002) Lipids are co-eluted with immunoglobulins G during purification by recombinant streptococcal protein G affinity chromatography. Journal of Immunological Methods, 271: 107– 111

B Akerstrom, et al. (1985) Protein G: a powerful tool for binding and detection of monoclonal and polyclonal antibodies. The Journal of Immunology, Vol 135, Issue 4: 2589-2592

Bengt Guss, et al. (1986) Structure of the IgG-binding regions of streptococcal protein G. The EMBO Journal, vol.5 no.7: 1567-1575

Bioclone

Technology

Protein A, G, A/G, and L

BcMag™ Protein A Magnetic Beads

BcMag™ Protein G Magnetic Beads

BcMag™ Protein A/G Magnetic Beads

BcMag™ Protein L Magnetic Beads

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General Reference

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