Monthly Archives: January 2020

Cyclic peptides as broad-spectrum antiviral agents

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Cyclic peptides as broad-spectrum antiviral agent

Cyclic peptides as broad-spectrum antiviral agents

Antiviral drugs and vaccines are the most powerful tools to combat viral diseases. Most drugs and vaccines only target a single virus. However, the broad-spectrum antivirals can be used for rapid management of new or drug-resistant viral strains. Cyclized peptides and peptide analogs are excellent examples of broad-spectrum antivirals.

An artificial peptide molecule was found to neutralize a broad range of group 1 influenza A viruses, including H5N1. The peptide design was based on complementarity determining region (CDR) loops have been reported for other viral targets. The optimized peptides bind to the highly conserved stem epitope and block the low pH-induced conformational rearrangements associated with membrane fusion.

These peptidic compounds and their advantageous biological properties should accelerate development of novel small molecule and peptide-based therapeutics against influenza virus.

The linear peptide is Suc-SQLRSLEYFEWLSQ-NH2. Three cyclization strategies were used: head to tail, side chain to side chain and side chain to tail. An ornithine (Orn) side chain was fused with the carboxyl terminus of β-alanine for lactam formation.

Check here for more details: Potent peptidic fusion inhibitors of influenza virus, Science 28 Sep 2017, DOI: 10.1126/science.aan0516

Lately, more broad-spectrum antiviral agents were found to target viruses. It was found that 55 compounds can target eight different RNA and DNA viruses. Dalbavancin is a novel lipo-glycopeptide antibiotic. The lipoglycopeptide disrupts bacterial cell wall formation by binding to
the terminal d-alanyl-d-alanine peptidoglycan sequence in Gram-positive bacteria in a linear, concentration-dependent manner. The dalbavancin has effects on echovirus 1, ezetimibe against HIV1 and Zika virus.

More details: https://www.ncbi.nlm.nih.gov/pubmed/29698664

Magnetic Beads: Expert Tips and Protocols for Effective Use

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Magnetic beads

Protein Purification Using Magnetic Beads: Top Tips for Success

Magnetic bead-based protein purification offers a powerful solution for various applications like high-throughput microscale purification, pull-down/CoIP experiments, and protein-protein or protein-DNA interaction studies. Here’s why magnetic beads are the top choice: they can be coated with specific affinity ligands for antigens, antibodies, proteins, or nucleic acids. Moreover, magnetic beads are non-porous and have a defined diameter, eliminating hidden surfaces where molecules can stick, leading to reduced background, simplified purification, and streamlined washing steps. Compared to traditional bead separation methods involving agarose, sepharose, or silica beads, magnetic bead separation stands out as the quickest, cleanest, and most efficient technique.

If you’re new to working with magnetic beads, here are some essential tips to ensure success:

  1. Thorough Resuspension: Ensure uniformity across aliquots by thoroughly resuspending your magnetic beads. These nano-superparamagnetic beads are covalently coated with highly functional groups, providing increased binding capacity and better dispersion. Since magnetic beads are composed of iron oxide and can settle over time, it’s crucial to vortex and resuspend them thoroughly before use to redisperse the beads.
  2. Enhanced Washing: Minimize non-specific binding by increasing the number of washing steps. Whether you’re using ethanol or the recommended wash buffer, make sure to use an adequate volume of wash solution to cover the bead pellet.
  3. Understanding Functional Groups: Different beads are covalently coated with various functional groups like maleimide, primary amine, NHS, carboxylic acid, purified streptavidin, protein A, reduced glutathione, nickel-charged nitrilotriacetic acid, or groups for DNA/RNA purification. These coatings, along with buffer conditions, affect bead properties. Understanding these specifics is essential for proper bead handling.
  4. Efficient Bead Capture: Magnetic beads typically form a pellet attracted to the magnet within a minute. Extend the attraction time to ensure efficient bead capture.
  5. Gentle Supernatant Removal: When removing the wash solution or supernatant, angle the pipette tip to avoid disturbing the magnetic bead pellet. Ensure that the tip doesn’t come into contact with the pellet.

By following these tips, you can make the most of magnetic bead-based protein purification, improving the efficiency and reliability of your experiments.