6fgo | pdb_00006fgo
Fc in complex with engineered calcium binding domain Z
Structural highlights
Function[IGG1_HUMAN] Immunoglobulins, also known as antibodies, are membrane-bound or secreted glycoproteins produced by B lymphocytes. In the recognition phase of humoral immunity, the membrane-bound immunoglobulins serve as receptors which, upon binding of a specific antigen, trigger the clonal expansion and differentiation of B lymphocytes into immunoglobulins-secreting plasma cells. Secreted immunoglobulins mediate the effector phase of humoral immunity, which results in the elimination of bound antigens (PubMed:22158414, PubMed:20176268). The antigen binding site is formed by the variable domain of one heavy chain, together with that of its associated light chain. Thus, each immunoglobulin has two antigen binding sites with remarkable affinity for a particular antigen. The variable domains are assembled by a process called V-(D)-J rearrangement and can then be subjected to somatic hypermutations which, after exposure to antigen and selection, allow affinity maturation for a particular antigen (PubMed:20176268, PubMed:17576170).[1] [2] [3] Publication Abstract from PubMedPresented here is an engineered protein domain, based on Protein A, that displays a calcium-dependent binding to antibodies. This protein, ZCa, is shown to efficiently function as an affinity ligand for mild purification of antibodies through elution with ethylenediaminetetraacetic acid (EDTA). Antibodies are commonly used tools in the area of biological sciences and as therapeutics, and the most commonly used approach for antibody purification is based on Protein A using acidic elution. Although this affinity-based method is robust and efficient, the requirement for low pH elution can be detrimental to the protein being purified. By introducing a calcium-binding loop in the Protein A-derived Z domain it has been re-engineered to provide efficient antibody purification under mild conditions. Through comprehensive analyses of the domain as well as the ZCa-Fc-complex the features of this domain are well understood. This novel protein domain provides a very valuable tool for effective and gentle antibody and Fc-fusion protein purification. Protein engineering allows for mild affinity-based elution of therapeutic antibodies.,Kanje S, Venskutonyte R, Scheffel J, Nilvebrant J, Lindkvist-Petersson K, Hober S J Mol Biol. 2018 Jun 7. pii: S0022-2836(18)30580-1. doi:, 10.1016/j.jmb.2018.06.004. PMID:29886013[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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