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United States Biological

USBio's Growing Line of Purification Products:
purification profileWe are expanding our line of purification products as well as adding some new immunology and microbiology reagents. USBio's modified Avidin provides a substantial improvement over native Avidin. High affinity to biotin is maintained, while background problems are minimized due to chemical modification on the protein. Our beads feature proprietary TargetLock chemistry, improving the chemical stability and durability of agarose beads upon repeated uses, making them an even greater value for your money.


Protein A

Protein G

Affinity Media
Blue Beads
Gelatin Beads
Heparin Beads

Tag-Binding Beads
Nickel Beads
Glutathione Beads

Activated Beads
Epoxy-Activated Beads
DVS-Activated Beads

Activated Carriers
Maleimide-Activated BSA
Maleimide-Activated OvA
Maleimide-Activated KLH

Antibody Purification
Ig-Thio-Capture Beads
Protein G Beads
Protein A Beads
Protein G
Protein A

Avidin Beads
Biotin-Capture Beads

Immuno Precipitation
Anti-Mouse Beads

Protein Size Makers
Biotinilated Protein MW Markers


Protein A, Protein G, and Protein L
Protein A, Protein G, and Protein L are commonly used to purify, immobilize or detect antibodies. Protein A and Protein G bind to the Fc region of IgGs. Protein L binds to antibodies through kappa light chain interactions. Protein A is generally preferred for rabbit, porcine, canine and feline IgG. Protein G has better binding capacity for a broader range of mouse and human IgG subclasses. Protein L binds to representatives of all antibody classes, including IgG, IgM, IgA, IgE and IgD but is only effective in binding certain subtypes of kappa light chains.


Newsletter Special:
10% off Anti-Mouse Beads, Protein A Beads, Protein G Beads
Goat Anti-Mouse IgG (whole molecule) is affinity purified on Mouse IgG affinity column using IgG isolated from pooled normal Mouse sera.
Protein A beads are produced using genetically engineered Protein A. Nonessential regions have been removed while leaving the IgG binding sites.
Protein G beads are produced using genetically engineered Protein G. Non-essential regions have been removed while leaving the IgG binding sites.


This month's Special:
Helicobacter pylori
Cag Antigen, and anti- Helicobacter pylori Cag

H1840-48 Helicobacter pylori Cag Antigen,
anti- Helicobacter pylori Cag

Helicobacter pylori is a Gram-negative, microaerophilic bacterium that inhabits various areas of the stomach and duodenum. It causes a chronic low-level inflammation of the stomach lining and is strongly linked to the development of duodenal and gastric ulcers and stomach cancer.

Helicobacter pylori

Helicobacter pylori

Affinity Chromatography
Specific Separation

Affinity chromatography makes use of specific binding interactions between molecules. A particular ligand is chemically immobilized or “coupled” to a solid support so that when a complex mixture is passed over the column, only those molecules having specific binding affinity to the ligand are purified.

Affinity purification generally involves the following steps: 1) Incubate crude sample with the immobilized ligand support material to allow the target molecule in the sample to bind to the immobilized ligand. 2) Wash away nonbound sample components from solid support, and 3) Elute and recover the target molecule from the immobilized ligand by altering the buffer conditions so that the binding interaction no longer occurs.

Depending on the type of molecule to be purified, its specificity, conditions under which it is stable, different types of ligands coupled to different types of support may be employed. As examples, two popular chromatographic media are Tag Binding Beads, such as Nickel or Glutathione coupled gels, or Activated Beads, such as epoxy-linked or divinyl sulphone-linked beads. All of these gels are based on the same support matrix, Sepharose CL-4B; but because of their different ligands, they are used for very different purposes.