Ionpair-π interactions favor cell penetration of arginine/tryptophan-rich cell-penetrating peptides.

Cell-penetrating peptides (CPPs) internalization occurs both by endocytosis and direct translocation through the cell membrane. These different entry routes suggest that molecular partners at the plasma membrane, phospholipids or glycosaminoglycans (GAGs), bind CPPs with different affinity or selectivity. The analysis of sequence-dependent interactions of CPPs with lipids and GAGs should lead to a better understanding of the molecular mechanisms underlying their internalization.

Quantitative fluorescence spectroscopy and flow cytometry analyses of cell-penetrating peptides internalization pathways: optimization, pitfalls, comparison with mass spectrometry quantification.

The mechanism of cell-penetrating peptides entry into cells is unclear, preventing the development of more efficient vectors for biotechnological or therapeutic purposes. Here, we developed a protocol relying on fluorometry to distinguish endocytosis from direct membrane translocation, using Penetratin, TAT and R9. The quantities of internalized CPPs measured by fluorometry in cell lysates converge with those obtained by our previously reported mass spectrometry quantification method.

Massive glycosaminoglycan-dependent entry of Trp-containing cell-penetrating peptides induced by exogenous sphingomyelinase or cholesterol depletion.

Among non-invasive cell delivery strategies, cell-penetrating peptide (CPP) vectors represent interesting new tools. To get fundamental knowledge about the still debated internalisation mechanisms of these peptides, we modified the membrane content of cells, typically by hydrolysis of sphingomyelin or depletion of cholesterol from the membrane outer leaflet. We quantified and visualised the effect of these viable cell surface treatments on the internalisation efficiency of different CPPs, among which the most studied Tat, R9, penetratin and analogues, that all carry the N-terminal biotin-Gly4 tag cargo.

Tryptophan within basic peptide sequences triggers glycosaminoglycan-dependent endocytosis.

Deciphering the structural requirements and mechanisms for internalization of cell-penetrating peptides (CPPs) is required to improve their delivery efficiency. Herein, a unique role of tryptophan (Trp) residues in the interaction and structuring of cationic CPP sequences with glycosaminoglycans (GAGs) has been characterized, in relation with cell internalization. Using isothermal titration calorimetry, circular dichroism, NMR, mass spectrometry, and phase-contrast microscopy, we compared the interaction of 7 basic CPPs with 5 classes of GAGs.

Nanoparticle-induced folding and fibril formation of coiled-coil-based model peptides.

Nanomedicine is a rapidly growing field that has the potential to deliver treatments for many illnesses. However, relatively little is known about the biological risks of nanoparticles. Some studies have shown that nanoparticles can have an impact on the aggregation properties of proteins, including fibril formation.

A 1 : 2 copper(II)-tripeptide complex for DNA binding and cleavage agent under physiological conditions.

A 1 : 2 copper-tripeptide complex, [Cu(II)(Boc-His-Gly-His-OMe)(2)](2+), was synthesized and structurally characterized. The absorption band at 577 nm suggests a square-planar geometry around Cu(II). The DNA-binding and DNA-cleavage properties of the Cu(II) complex were investigated.

Synthesis, characterization, and DNA-binding studies of mononuclear copper(II)-phenanthroline-tyrosine complex.

The mononuclear complex [Cu(II)(phen)(L-Tyr)(H(2)O)] was synthesized and structurally characterized by elemental analysis, magnetic susceptibility, UV/VIS, IR, and EPR spectroscopy, and ESI mass spectrometry. The electronic and EPR spectral data suggest a square-pyramidal geometry around Cu(II). Absorption spectra, thermal denaturation, and fluorescence-spectroscopic studies were conducted to assess the interaction of the Cu(II) complex with calf thymus DNA (CT DNA).

Synthesis and DNA binding/cleavage of mononuclear copper(II) phenanthroline/bipyridine proline complexes.

The complexes [Cu(II)(phen)(L-Pro)(H2O)]+ ClO4(-) (1; phen = 1,10-phenanthroline) and [Cu(II)(bipy)(L-Pro)(H2O)]+ ClO4(-) (2; bipy = 2,2'-bipyridine) were synthesized and characterized by IR, magnetic susceptibility, UV/VIS, EPR, ESI-MS, elemental analysis, and theoretical calculations. The metal center was found in a square-pyramidal geometry. UV/VIS, thermal-denaturation, and fluorescence-spectroscopic studies were conducted to assess the interaction of the complexes with CT-DNA.

Mixed-ligand copper(II)-phenanthroline-dipeptide complexes: synthesis, characterization, and DNA-cleavage properties.

The mixed-ligand complexes [Cu(II)(HisLeu)(phen)](+) (1) and [Cu(II)(HisSer)(phen)](+) (2; phen=1,10-phenanthroline) were synthesized and characterized. The intercalative interaction of the Cu(II) complexes with calf-thymus DNA (CT-DNA) was probed by UV/VIS and fluorescence titration, as well as by thermal-denaturation experiments, and the intrinsic binding constants (K(b)) for the complexes with 1 and 2 were 4.2x10(3) and 4.

A new S4-ligated zinc-peptide 1:2 complex for the hydrolytic cleavage of DNA.

A new sulfur-ligated Zn-peptide 1:2 complex, [Zn(II)(Boc-NH-Cys-Gly-Cys-OMe)2]2- (2), was prepared, characterized, and tested for its DNA-binding and -cleavage properties. Complex 2 was found to cleave DNA hydrolytically. The negative charge in 2 reduces the affinity of the complex for DNA, and enhances its binding specificity.

Novel peptide-based copper(II) complexes for total hydrolytic cleavage of DNA.

Stable Cu(II) complexes with histamine- and histidine-containing dipeptides histidylserine and histidylphenylalanine have been developed. Their interaction in solution has been investigated, and the stability of their complexes was determined. The nature of binding in these complexes has been explained with the help of potentiometric pH titrations and 1H-NMR spectroscopy.