Design, Synthesis, and Application of a Library of Supramolecular Structures Formed by N-Lipidated Peptides Immobilized on Cellulose. Artificial Receptors

Selection of collagen IV fragments forming the outer sphere of the native protein: Assessment of biological activity for regenerative medicine

The aim of this research was to select the fragments that make up the outer layer of the collagen IV (COL4A6) protein and to assess their potential usefulness for regenerative medicine. It was expected that because protein-protein interactions take place via contact between external domains, the set of peptides forming the outer sphere of collagen IV will determine its interaction with other proteins. Cellulose-immobilized protein fragment libraries treated with polyclonal anti-collagen IV antibodies were used to select the peptides forming the outer sphere of collagen IV. In the first test, 33 peptides that strongly interacted with the polyclonal anti-collagen IV antibodies were selected from a library of non-overlapping fragments of collagen IV. The selected fragments of collagen IV (cleaved from the cellulose matrix) were tested for their cytotoxicity, their effects on cell viability and proliferation, and their impact on the formation of reactive oxygen species (ROS). The studies used RAW 264.7 mouse macrophage cells and Hs 680.Tr human fibroblasts. PrestoBlue, ToxiLight™, and ToxiLight 100% Lysis Control assays were conducted. The viability of fibroblasts cultured with the addition of increasing concentrations of the peptide mix did not show statistically significant differences from the control. Fragments 161-170, 221-230, 721-730, 1331-1340, 1521-1530, and 1661-1670 of COL4A6 were examined for cytotoxicity against BJ normal human foreskin fibroblasts. None of the collagen fragments were found to be cytotoxic. Further research is underway on the potential uses of collagen IV fragments in regenerative medicine.

N-Lipidated Amino Acids and Peptides Immobilizedon Cellulose Able to Split Amide Bonds

N-lipidated short peptides and amino acids immobilized on the cellulose were used as catalysts cleaved amide bonds under biomimetic conditions. In order to select catalytically most active derivatives a library of 156 N-lipidated amino acids, dipeptides and tripeptides immobilized on cellulose was obtained. The library was synthesized from serine, histidine and glutamic acid peptides N-acylated with heptanoic, octanoic, hexadecanoic and (E)-octadec-9-enoic acids. Catalytic efficiency was monitored by spectrophotometric determination of p-nitroaniline formed by the hydrolysis of a 0.1 M solution of Z-Leu-NP. The most active 8 structures contained tripeptide fragment with 1-3 serine residues. It has been found that incorporation of metal ions into catalytic pockets increase the activity of the synzymes. The structures of the 17 most active catalysts selected from the library of complexes obtained with Cu²⁺ ion varied from 16 derivatives complexed with Zn²⁺ ion. For all of them, a very high reaction rate during the preliminary phase of measurements was followed by a substantial slowdown after 1 h. The catalytic activity gradually diminished after subsequent re-use. HPLC analysis of amide bond splitting confirmed that substrate consumption proceeded in two stages. In the preliminary stage 24–40% of the substrate was rapidly hydrolysed followed by the substantially lower reaction rate. Nevertheless, using the most competent synzymes product of hydrolysis was formed with a yield of 60–83% after 48h under mild and strictly biomimetic conditions.

Towards Intelligent Drug Design System: Application of Artificial Dipeptide Receptor Library in QSAR-Oriented Studies

The pharmacophore properties of a new series of potential purinoreceptor (P2X) inhibitors determined using a coupled neural network and the partial least squares method with iterative variable elimination (IVE-PLS) are presented in a ligand-based comparative study of the molecular surface by comparative molecular surface analysis (CoMSA). Moreover, we focused on the interpretation of noticeable variations in the potential selectiveness of interactions of individual inhibitor-receptors due to their physicochemical properties; therefore, the library of artificial dipeptide receptors (ADP) was designed and examined. The resulting library response to individual inhibitors was arranged in the array, preprocessed and transformed by the principal component analysis (PCA) and PLS procedures. A dominant absolute contribution to PC1 of the Glu attached to heptanoic gating acid and Phe bonded to the linker m-phenylenediamine/triazine scaffold was revealed by the PCA. The IVE-PLS procedure indicated the receptor systems with predominant Pro bonded to the linker and Glu, Gln, Cys and Val directly attached to the gating acid. The proposed comprehensive ligand-based and simplified structure-based methodology allows the in-depth study of the performance of peptide receptors against the tested set of compounds.

Carbon nanotubes functionalized with folic acid attached via biomimetic peptide linker

AIM

Anchoring folic acid (FA) with a biomimetic peptidic linker resistant to proteolytic degradation to act as a homing device on functionalized carbon nanotubes.

MATERIALS & METHODS

Ethylenediamine was attached to oxidized multiwalled carbon nanotubes (MWNTs) using 4-(4,6-dimethoxy-[1,3,5]triazin-2-yl)-4-methylmorpholinium tetrafluoroborate. FA was coupled with 6-aminohexanoic acid and derivatives of β-alanine, affording four intermediates, which connected to the MWNTs via peptidic linkers of various lengths.

RESULTS

Biomimetic nanomaterials were produced with FA as a homing molecule. The structure and properties of the nanomaterials were analyzed, confirming the versatility of the peptides used as linkers.

CONCLUSION

Conjugates of FA attached to MWNTs via peptide linkers prepared from β-alanine residues are resistant to proteolytic degradation. Viability in colon cancer cells and normal colonocytes confirmed their lack of cytotoxicity.

Synthesis, structure and magnetism of homodinuclear complexes of Co, Ni and Cu supported by a novel bitriazine scaffold

Btzn (1), an amine-functionalized bi(1,3,5-triazine) 4,4'-(NH(2))(2)-6,6'-(NHC(6)H(5))(2)-2,2'-(1,3,5-C(3)N(3))(2), is reported, and its coordination with Co, Ni and Cu is explored. Reactions of metal salts (2 equiv) with Btzn (1 equiv) result in dimeric species [(Btzn)Co(2)(NCS)(4)(EtOH)(2)(DMF)(2)], (2), [(Btzn)Ni(2)(η(1)-ONO(2))(2)(MeOH)(4)(DMF)(2)]·2[NO(3)], (3), [(Btzn)Cu(2)Cl(4)(DMF)(2)], (4), and [(Btzn)Cu(2)(η(2)-O(2)NO)(2)(OH(2))(2)(DMF)(2)]·2[NO(3)], (5). These complexes are the first examples of the coordination of transition metals with bi(1,3,5-triazine) ligands. Their structures display a bridging bis-bidentate coordination mode for Btzn. Variable-temperature magnetic susceptibility of the complexes reveals antiferromagnetic exchange between the spin carriers, with calculated exchange coupling values (J) of -4.7 cm(-1) for 3, -18.2 cm(-1) for 4, and -5.5 cm(-1) for 5. An in-depth evaluation of the metal geometry highlights the inefficient overlap of the magnetic d-orbitals through the bridging ligand, most likely leading to reduced delocalization and coupling.

Structure-activity relationship in binding ligands to library of artificial receptors: the search for biocompatible sensor

Structure-activity relationship (SAR) analysis was applied for studies of docking of colored ligands to library of artificial receptors formed by self-assembly of N-lipidated amino acids immobilised on the cellulose support. The studies show that the binding depends mainly on the structure of amino acid fragment but influence of N-lipidic fragment is less important.

Application of a library of artificial receptors formed by the self-organization of N-lipidated peptides immobilized on cellulose in studying the effects of the incorporation of a fluorine atom

A library of artificial receptors formed by the self-organization of N-lipidated peptides attached to cellulose via m-aminophenylamino-1,3,5-triazine was used for docking pairs of small colorless N-phenylpiperazines with and without a fluorine atom in the phenyl ring. The interactions of guests with the receptors were visualized by using competitive adsorption-desorption of an appropriate reporter dye. Several library members demonstrated attributes characteristic of the detection of alterations in the guest structure caused by the substitution of one hydrogen atom with fluorine. Analysis of the binding pattern of N-phenylpiperazine derivatives showed two characteristic bonding patterns: one with stronger binding of fluorinated analogues and weaker binding of native phenyl substituted analogues by the most of the receptors studied and another one with stronger binding of native hydrogen substituted compounds and respectively weaker binding of fluorinated analogues of guest molecules by receptors with tryptophan inside the binding pocket.