Antibody fragment

Antibody Fragment

An antibody fragment is a portion of an antibody that retains the ability to bind to an antigen. Antibodies, also known as immunoglobulins, are Y-shaped proteins produced by the immune system to identify and neutralize foreign objects such as bacteria and viruses. Antibody fragments are derived from these full-length antibodies and are used in various therapeutic and diagnostic applications due to their smaller size and unique properties.

Types of Antibody Fragments

There are several types of antibody fragments, each with distinct characteristics and uses:

• Fab: The Fab (Fragment antigen-binding) is a region on an antibody that binds to antigens. It is composed of one constant and one variable domain of each of the heavy and the light chain. Fab fragments are produced by enzymatic digestion of antibodies with papain.

• F(ab')2: This fragment is similar to the Fab but includes two antigen-binding Fab portions linked by a disulfide bond. It is produced by pepsin digestion of antibodies.

• scFv: A single-chain variable fragment is a fusion protein of the variable regions of the heavy (VH) and light chains (VL) of immunoglobulins, connected with a short linker peptide. scFvs are often used in research and therapeutic applications due to their small size and ability to penetrate tissues.

• Nanobodies: These are single-domain antibodies derived from heavy-chain-only antibodies found in camelids. Nanobodies are the smallest antibody fragments and have unique properties such as high stability and solubility.

Applications

Antibody fragments are used in a variety of applications due to their smaller size, which allows for better tissue penetration and faster clearance from the body. Some of the key applications include:

• Therapeutics: Antibody fragments are used in the treatment of diseases such as cancer, autoimmune disorders, and infectious diseases. Their ability to target specific antigens makes them ideal for targeted therapy.

• Diagnostics: In diagnostic assays, antibody fragments are used to detect the presence of specific antigens. Their small size and high specificity make them suitable for use in imaging and biosensors.

• Research: Antibody fragments are valuable tools in research for studying protein-protein interactions, cell signaling pathways, and other biological processes.

Advantages

Antibody fragments offer several advantages over full-length antibodies:

• Smaller size: This allows for better tissue penetration and faster clearance from the body.

• Reduced immunogenicity: Smaller fragments are less likely to elicit an immune response.

• Ease of production: Antibody fragments can be produced in bacterial systems, which is often more cost-effective than producing full-length antibodies in mammalian cells.

Also see

• Monoclonal antibody
• Polyclonal antibody
• Antigen
• Immunotherapy
• Biotechnology