Reaching the target – a novel cell penetration assay provides new insights into the design and intracellular compartmentalization of biotherapeutics

Feb 21, 2019 4:21:51 PM

There have been massive advances in the development of biotherapeutics but progress has been slow in targeting intracellular processes due in part to the difficulty of measuring cell penetration and distribution between intracellular compartments and organelles. A research group based at Tufts University, USA, has developed a novel assay, the Chloroalkane Penetration Assay (CAPA), as a powerful tool to meet this challenge. They have shown how CAPA can help in following the modulation of biomolecule cell penetration, including structure-penetration profiling of bioactive stapled peptides and peptides fused to cell-penetrating sequences, measuring the effect of environmental factors on penetration, and tracing the movement of potential biotherapeutics between organelles.

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Topics: Peptide synthesis, Tribute peptide synthesizer, Biotherapeutics development, Cell penetration assay

Cationic cell penetrating peptides with fatty acyl groups improve siRNA-delivery by chitosan for gene therapy

Oct 16, 2018 10:00:00 AM

After thirty years of promise and setbacks, a number of gene therapies for inherited immune disorders, like hemophilia, eye and neurodegenerative disorders, and lymphoid cancers have recently been approved in the United States and Europe or are anticipated to receive approval in the near future. One approach to gene therapy is to suppress the expression of specific proteins by gene silencing using siRNA. Viral delivery systems can have issues of immunogenicity and mutagenesis. This has stimulated the development of non-viral delivery systems. El-Sayed and collaborators based in Egypt and the USA have shown that chitosan complexed with fatty-acyl derivatives of a cationic cell-penetrating peptide, CGKRK, shows promise as a method for delivering intact short interfering RNA (siRNA) to breast cancer cells in vitro.

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Topics: Peptide synthesis, Tribute peptide synthesizer, Gene therapy, Cell penetrating peptide, siRNA delivery

Enabling identification of phosphorylated cysteine: Novel chemoselective synthetic and analytical methods

Dec 5, 2017 10:32:31 AM

Protein phosphorylation plays a key role in the regulation of signaling pathways and many other cellular processes. Studies of phosphorylation have focused on serine, threonine and tyrosine amino-acid side chains, while the phosphorylation of other amino acids, such as phospho-histidine (pHis), -arginine (pArg), -lysine (pLys) and -cysteine (pCys), is less well understood. Studies have been hindered by technical limitations, primarily acid lability. To address this problem, Jordi Bertran-Vicente and colleagues have developed a novel chemoselective and stereochemically defined phosphorylation strategy for Cys residues.  The method employs the nucleophilic reactivity of P(III)-reagents (phosphites) with electrophilic disulfides. The research team has also developed a mass spectrometry-based proteomic approach to identify and characterize pCys sites that naturally occur in peptides. 

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Topics: Peptide synthesis, Tribute, Tribute peptide synthesizer, pCys, Protein phosphorylation