PureBiotech LLC Online - MBPD

Rapid, gentle & complete immobilization
Easily automated
No need for surfactants
Will not clump or adhere to hydrophobic surfaces
Cost effective
Higher yields of concentrated target protein
Complementary to MPG™ Protein G

PureBiotech LLC's Protein A particles are Magnetic Porous Glass (MPG^™) particles to which protein A has been covalently attached. MPG^™ Protein A particles possess antibody binding properties similar to unconjugated protein A. The nominal binding capacity of 1 mg of particles is between 50 - 75 µg of immunoglobulin for strong species such as rabbit and human IgG.

Use of magnetic particles eliminates the need for centrifugation, spin baskets, and columns. Magnetic particles are also easier to automate and provide greater flexibility in assay configuration. This format reduces assay/ purification time by promoting rapid and complete washing involving few steps and a single tube. The high surface area and high loading of MPG^™ Protein A promote quick capture of target antibody. Under optimal conditions purified immunoglobulin can be recovered from MPG^™ Protein A in as little as 15 minutes. Magnetic porous glass particle technology also allows the purified target protein to be recovered in a more concentrated form compared to alternative formats including immobilized protein A microplates. More than 75% recovery of captured antibody can be achieved in as little as 10 µl volume while giving protein concentrations greater than 4 mg/ml.

MPG^™ particles give higher yields of concentrated target protein than other available magnetic protein A particles. In addition to having higher binding capacity, magnetic porous glass particles do not clump. Polystyrene magnetic particles tend to clump and adhere to hydrophobic surfaces when surfactants or similar agents are eliminated from the buffers. This results in loss of particles to pipette tips, tube walls etc. and increased elution volumes, which in turn lowers yield and dilutes recovered target protein (Table 1). MPG^™ Protein A performs well in high salt buffers without the presence of surfactants.

Table 1	MPG^™ Protein A	Polystyrene Protein A #1	Polystyrene Protein A #2
Total Binding Capacity^a	53±1	33±2	46±1
Recovered in 3x50µl^a (%)	47±1 (88%)	15±2 (44%)	39±1 (84%)

^a Values represent the mean±SEM of 11 samples, expressed as µg IgG/mg particles

Table1: 3 mg of three brands of magnetic protein A particles were incubated with an excess of 10% rabbit serum in 0.15M NaCl, 1 M glycine, pH8.6, washed 2 times in the same buffer and then washed 2 times in PBS, IgG was then eluted in 0.1M glycine, pH 2.5.

MPG^™ Protein A particles make mg scale magnetic batch purification of immunoglobulins economically feasible (see Figure 1). MPG^™ Protein A can be regenerated up to 12 times while still providing greater than 90% of initial binding capacity. Regeneration is easy to do and takes only 5 minutes.

Figure 1. Purity of rabbit IgG recovered from MPG^™ Protein A particles. 3 mg MPG^™ Protein A was mixed with 0.5 ml 10% normal rabbit serum in 1 M glycine-HCl pH 8.6, 0.15 M NaCl (lane 2, 10 µg). After washing four times with an equal volume of the same buffer (twice) and PBS (twice), IgG was recovered with 0.1M glycine, pH 2.5 and neutralized with 0.1 volume of 1 M NaHPO₄, pH 9.0. The regenerated particles were neutralized with 1 M glycine-HCl pH 8.6, 0.15 M NaCl and recycled with fresh serum for a total of 12 purifications. Samples (2.5 µg) from the initial (lane 3) and final (lane 4) purification were analyzed on a reducing SDS 12% polyacrylamide gel along with a commercial rabbit IgG standard (lane 1) and rabbit IgG purified from the same serum using PROSEP^™-A High Capacity (lane 5). The gel was stained with SYPRO^™ Ruby.

APPLICATIONS:

Small scale affinity purification
IgG, Fab, Fc purification
Immunoprecipitation reactions
Single or automated immunoassays & bioassays
Separation of unbound labeled tracers
Oriented IgG conjugation
Protein sequencing

RELATED SECTIONS:

MPG^™ Protein A Products
Product No.	Product Description	Unit	Price
MPGPA0501	MPG^™ Protein A	1 ml	$105.00
MPGPA0505	MPG^™ Protein A	5 ml	$435.00
MPGPA0510	MPG^™ Protein A	10 ml	$800.00

Packed as a 1% suspension in PBS with biocide and BSA.