Growth factor- and adhesion protein-like components of fetal calf serum can significantly enhance the intracellular delivery of Peptide nucleic acids.

Evidence is presented that components of fetal calf serum (FCS) can significantly enhance the splicing correction activity of peptide nucleic acids (PNA) in HeLa pLuc 705 cells. The effect proved more pronounced for PNAs bearing fluorescence tags and relies on the ability of specific components of FCS to mediate a mainly nonendocytotic intracellular delivery of PNA. Attempts to isolate and characterize the active serum components using PNA-loaded beads and nano-LC-ESI mass spectrometry revealed the growth-factor related inter-alpha-trypsin inhibitor and the adhesion protein fibronectin to be substantially responsible for the delivery activity of FCS.

Enhancement of intracellular concentration and biological activity of PNA after conjugation with a cell-penetrating synthetic model peptide.

In order to evaluate the ability of the cell-penetrating alpha-helical amphipathic model peptide KLALKLALKALKAALKLA-NH(2) (MAP) to deliver peptide nucleic acids (PNAs) into mammalian cells, MAP was covalently linked to the 12-mer PNA 5'-GGAGCAGGAAAG-3' directed against the mRNA of the nociceptin/orphanin FQ receptor. The cellular uptake of both the naked PNA and its MAP-conjugate was studied by means of capillary electrophoresis combined with laser-induced fluorescence detection, confocal laser scanning microscopy and fluorescence-activated cell sorting. Incubation with the fluorescein-labelled PNA-peptide conjugate led to three- and eightfold higher intracellular concentrations in neonatal rat cardiomyocytes and CHO cells, respectively, than found after exposure of the cells to the naked PNA.

Real-time determination of telomerase activity in cell extracts using an optical biosensor.

A biosensoric approach has been developed to determine the activity of telomerase in tumor cell lysates. An optical sensor, the grating coupler, was used to monitor the association and dissociation of unlabeled compounds on the sensor surface in real time, by virtue of an evanescent field. An oligonucleotide was immobilized on the surface of the optical biosensor and linked with two other oligonucleotides by complementary sequences in an overlapping manner.

Cyclization of all-L-Pentapeptides by Means of 1-Hydroxy-7-azabenzotriazole-Derived Uronium and Phosphonium Reagents.

Due to their restricted conformational flexibility, cyclic peptides are of great interest in connection with structure-activity relationships, especially the elucidation of bioactive conformations. For linear peptides that do not contain turn structure-inducing amino acid residues, the cyclization reaction may be an inherently improbable or slow process, and side reactions, such as cyclodimerization and epimerization at the C-terminal residue, may dominate. A number of 1-hydroxy-7-azabenzotriazole-based onium salts were examined for cyclization of thymopentin-derived pentapeptides and the results compared with data from more conventional coupling reagents.