Fetal bovine serum albumin inhibits antimicrobial peptide activity and binds drug only in complex with α1-antitrypsin

Several antimicrobial peptides (AMPs) have been developed for the treatment of infections caused by antibiotic-resistant microbes, but their applications are primarily limited to topical infections because in circulation they are bound and inhibited by serum proteins. Here we have found that some AMPs, such as TP4 from fish tilapia, and drugs, such as antipyretic ibuprofen, were bound by bovine serum albumin only in complex with alpha 1-antitrypsin which is linked by disulfide bond. They existed in dimeric complex (2 albumin -2 alpha 1-antitrypsin) in the bovine serum only at fetal stage, but not after birth. The hydrophobic residues of TP4 were responsible for its binding to the complex. Since bovine serum is a major supplement in most cell culture media, therefore the existence and depletion of active albumin/alpha 1-antitrypsin complex are very important for the assay and production of biomolecules.

Automated summary

Some AMPs and drugs are bound and inhibited by serum proteins in complex with alpha 1-antitrypsin in bovine serum only at fetal stage, with TP4's hydrophobic residues responsible for its binding to the complex. This active albumin/alpha 1-antitrypsin complex's existence and depletion are important for biomolecule assay and production due to bovine serum's prevalence in cell culture media.