JB-95 peptide

• Handling and Storage of Synthetic Peptides
• Material Safety Data Sheets (MSDS)

Batch to batch variation of the purity

JB-95 is a macrocyclic β-hairpin peptide exhibiting potent antimicrobial activity against Escherichia coli. Structural studies reveal a stable β-hairpin conformation, facilitated by type II' β-turns and regular β-strands. The peptide selectively disrupts the outer membrane (OM) of E. coli without affecting the inner membrane, as evidenced by electron microscopy and fluorescence assays. Proteomic and photolabeling experiments indicate that JB-95 interacts with β-barrel OM proteins, including BamA and LptD, leading to rapid depletion of these proteins and induction of membrane stress responses. This disruption occurs through localized interactions, causing OM breaches and compromising membrane integrity.

The mechanism of JB-95 involves targeting OM protein clusters, distinct from traditional membrane-lytic peptides. Unlike polymyxin B, JB-95 does not permeabilize the cytoplasmic membrane, as shown by the absence of cytoplasmic enzyme release. Its punctate binding pattern, observed via fluorescence microscopy, suggests association with OM protein islands. The peptide's unique β-hairpin structure and selective OM disruption highlight its potential as a scaffold for antibiotics targeting Gram-negative bacterial envelopes.

• Urfer M, Bogdanovic J, Lo Monte F, Moehle K, Zerbe K, Omasits U, Ahrens CH, Pessi G, Eberl L, Robinson JA. A Peptidomimetic Antibiotic Targets Outer Membrane Proteins and Disrupts Selectively the Outer Membrane in Escherichia coli. J Biol Chem. 2016 Jan 22;291(4):1921-1932. doi: 10.1074/jbc.M115.691725. Epub 2015 Dec 1. PMID: 26627837; PMCID: PMC4722468.

Trifluoroacetic acid (TFA) is a common counterion from the purification process using High-Performance Liquid Chromatography (HPLC). The presence of TFA can affect the peptide's net weight, appearance, and solubility.

Impact on Net Weight: The TFA salt contributes to the total mass of the product. In most cases, the peptide content constitutes >80% of the total weight, with TFA accounting for the remainder.

Solubility: TFA salts generally enhance the solubility of peptides in aqueous solutions.

In Biological Assays: For most standard in vitro assays, the residual TFA levels do not cause interference. However, for highly sensitive cellular or biochemical studies, please be aware of its presence.