Stepwise solid-phase synthesis of nucleopeptide Phac-Ser(p5′CATCAT)-Gly-Asp-OH from adenovirus-2 nucleoprotein

LNA 5'-phosphoramidites for 5'→3'-oligonucleotide synthesis

Hereby we report an efficient synthesis of LNA thymine and LNA 5-methylcytosine 5'-phosphoramidites, allowing incorporation of LNA thymine and LNA 5-methylcytosine into oligonucleotides synthesized in the 5'→3' direction. Key steps include regioselective enzymatic benzoylation of the 5'-hydroxy group of unprotected LNA thymine, and subsequent 4,4'-dimethoxytritylation of the 3'-hydroxy group of the O5'-benzoylated LNA thymine nucleoside.

Solid-phase synthesis of oligonucleotide conjugates useful for delivery and targeting of potential nucleic acid therapeutics

Olignucleotide-based drugs show promise as a novel form of chemotherapy. Among the hurdles that have to be overcome on the way of applicable nucleic acid therapeutics, inefficient cellular uptake and subsequent release from endosomes to cytoplasm appear to be the most severe ones. Covalent conjugation of oligonucleotides to molecules that expectedly facilitate the internalization, targets the conjugate to a specific cell-type or improves the parmacokinetics offers a possible way to combat against these shortcomings. Since workable chemistry is a prerequisite for biological studies, development of efficient and reproducible methods for preparation of various types of oligonucleotide conjugates has become a subject of considerable importance. The present review summarizes the advances made in the solid-supported synthesis of oligonucleotide conjugates aimed at facilitating the delivery and targeting of nucleic acid drugs.

Peptide conjugates as tools for the study of biological signal transduction

Today, many biological phenomena are being investigated and understood in molecular detail, and organic chemistry is increasingly being directed towards biological phenomena. This review is intended to highlight this interplay of organic chemistry and biology, using biological signal transduction as an example. Lipo-, glyco-, phospho- and nucleoproteins play key roles in the processes whereby chemical signals are passed across cell membranes and further to the cell nucleus. For the study of the biological phenomena associated with these protein conjugates, structurally well-defined peptides containing the characteristic linkage region of the peptide backbone with the lipid, the carbohydrate or the phosphoric acid ester can provide valuable tools. The multi-functionality and pronounced acid- and base-lability of such compounds renders their synthesis a formidable challenge to conventional organic synthesis. However, the recent development of enzymatic protecting groups, provides one of the central techniques which, when coupled with classic chemical synthesis, can provide access to these complex and sensitive biologically relevant peptide conjugates under particularly mild conditions and with high selectivity.

A new solid-phase synthesis of oligonucleotides 3'-conjugated with peptides

A convenient 'on line' solid-phase synthesis of oligonucleotides conjugated at the 3'-end with peptides by means of a polymeric support linking the first nucleoside via the base has been developed. A 17-mer designed for antisense experiments against HIV-1, linking at the 3'-terminus the tripeptide Gly-Gly-His, was prepared in good yields and characterized by MALDI-TOF mass spectrometry.