Using Chemical Approaches to Understand RNA Structure and Function in Biology

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Conformation and self-association of peptide amphiphiles based on the KTTKS collagen sequence

Studying peptide amphiphiles (PAs), we investigate the influence of alkyl chain length on the aggregation behavior of the collagen-derived peptide KTTKS with applications ranging from antiwrinkle cosmetic creams to potential uses in regenerative medicine. We have studied synthetic peptides amphiphiles C14− KTTKS (myristoyl Lys-Thr-Thr-Lys-Ser) and C18−KTTKS(stearoyl-Lys-Thr Thr-Lys-Ser) to investigate in detail their physicochemical properties. It is presumed that the hydrophobic chain in these self-assembling peptide amphiphiles enhances peptide permeation across the skin compared to KTTKS alone. Subsequently Cn−KTTKS should act as a prodrug and release the peptide by enzymatic cleavage. Our results should be useful in the further development of molecules with collagen-stimulating activity

Chemistry of Peptide-Oligonucleotide Conjugates: A Review

Peptide-oligonucleotide conjugates (POCs) represent one of the increasingly successful albeit costly approaches to increasing the cellular uptake, tissue delivery, bioavailability, and, thus, overall efficiency of therapeutic nucleic acids, such as, antisense oligonucleotides and small interfering RNAs. This review puts the subject of chemical synthesis of POCs into the wider context of therapeutic oligonucleotides and the problem of nucleic acid drug delivery, cell-penetrating peptide structural types, the mechanisms of their intracellular transport, and the ways of application, which include the formation of non-covalent complexes with oligonucleotides (peptide additives) or covalent conjugation. The main strategies for the synthesis of POCs are viewed in detail, which are conceptually divided into (a) the stepwise solid-phase synthesis approach and (b) post-synthetic conjugation either in solution or on the solid phase, especially by means of various click chemistries. The relative advantages and disadvantages of both strategies are discussed and compared

New TFA-Free Cleavage and Final Deprotection in Fmoc Solid-Phase Peptide Synthesis: Dilute HCl in Fluoro Alcohol

A novel method for cleaving from resin and removing acid-labile protecting groups for the Fmoc solid-phase peptide synthesis is described. 0.1 N HCl in hexafluoroisopropanol or trifluoroethanol cleanly and rapidly removes the <i>tert</i>-butyl ester and ether, Boc, trityl, and Pbf groups and cleaves the common resin linkers: Wang, HMPA, Rink amide, and PAL. Addition of just 5–10% of a hydrogen-bonding solvent considerably retards or even fully inhibits the reaction. However, a non-hydrogen-bonding solvent is tolerated

Uridine 2′‐Carbamates: Facile Tools for Oligonucleotide 2′‐Functionalization

A facile method for preparation of uridine 2′‐carbamate derivatives based on reaction of 3′,5′‐disilyl‐protected uridine with 1,1′‐carbonyldiimidazole followed by treatment with an aliphatic amine is presented. A phosphoramidite monomer suitable for automated oligonucleotide synthesis is obtained in a few steps. The compounds are useful for the introduction of various labels and modifications into an oligonucleotide chain. Although 2′‐carbamate modification is somewhat destabilizing for DNA‐DNA and DNA‐RNA duplexes, it is suitable for the direction of ligands into the minor groove of duplexes or at non‐base‐paired sites (e.g., loops and bulges) of oligonucleotides. Pyrene‐modified oligonucleotide 2′‐carbamates show a considerable increase in fluorescence intensity upon hybridization to a complementary RNA (but not DNA).Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153179/1/cpnc0421.pd

Oligonucleotides with 2′-O-carboxymethyl group: Synthesis and 2′-conjugation via amide bond formation on solid phase

An efficient method for synthesis of oligonucleotide 2′-conjugates via amide bond formation on solid phase is described. Protected oligonucleotides containing a 2′-O-carboxymethyl group were obtained by use of a novel uridine 3′-phosphoramidite, where the carboxylic acid moiety was introduced as its allyl ester. This protecting group is stable to the conditions used in solid-phase oligonucleotide assembly, but easily removed by Pd(0) and morpholine treatment. 2′-O-Carboxymethylated oligonucleotides were then efficiently conjugated on a solid support under normal peptide coupling conditions to various amines or to the N-termini of small peptides to give products of high purity in good yield. The method is well suited in principle for the preparation of peptide-oligonucleotide conjugates containing an amide linkage between the 2′-position of an oligonucleotide and the N-terminus of a peptide

Data set on the synthesis and properties of 2′,3′-dideoxyuridine triphosphate conjugated to SiO2 nanoparticles

SiO2 nanoparticles were used as a transport system for cellular delivery of phosphorylated 2′,3′-dideoxyuridine to increase its anticancer potency. This data set is related to the research article entitled “2′,3′-Dideoxyuridine triphosphate conjugated to SiO2 nanoparticles: synthesis and evaluation of antiproliferative activity” (Vasilyeva et al., 2018) [1]. It includes a protocol for the synthesis of 2′,3′-dideoxyuridine-5′-{N-[4-(prop-2-yn-1-yloxy)butyl]-γ-amino}-triphosphate, its identification by NMR, IR and ESI-MS, experimental procedure of covalent attachment to SiO2 nanoparticles with via Cu-catalyzed click-chemistry, experimental data on chemical stability of the conjugate at different pH values and cytotoxicity assessment of antiproliferative effect of the conjugate. Keywords: Cellular delivery, Click-chemistry, Phosphorylated nucleosides, MCF7 cells, Cytotoxicit

Design and Properties of Ligand-Conjugated Guanine Oligonucleotides for Recovery of Mutated G-Quadruplexes

The formation of a guanine quadruplex DNA structure (G4) is known to repress the expression of certain cancer-related genes. Consequently, a mutated G4 sequence can affect quadruplex formation and induce cancer progression. In this study, we developed an oligonucleotide derivative consisting of a ligand-containing guanine tract that replaces the mutated G4 guanine tract at the promoter of the vascular endothelial growth factor (VEGF) gene. A ligand moiety consisting of three types of polyaromatic hydrocarbons, pyrene, anthracene, and perylene, was attached to either the 3&#8242; or 5&#8242; end of the guanine tract. Each of the ligand-conjugated guanine tracts, with the exception of anthracene derivatives, combined with other intact guanine tracts to form an intermolecular G4 on the mutated VEGF promoter. This intermolecular G4, exhibiting parallel topology and high thermal stability, enabled VEGF G4 formation to be recovered from the mutated sequence. Stability of the intramolecular G4 increased with the size of the conjugated ligand. However, suppression of intermolecular G4 replication was uniquely dependent on whether the ligand was attached to the 3&#8242; or 5&#8242; end of the guanine tract. These results indicate that binding to either the top or bottom guanine quartet affects unfolding kinetics due to polarization in DNA polymerase processivity. Our findings provide a novel strategy for recovering G4 formation in case of damage, and fine-tuning processes such as replication and transcription