Editorial [Hot topic: Bioorganic Chemistry (Guest Editor: Harri Lonnberg)]

This thematic issue of bioorganic chemistry is largely focused on chemistry of oligonucleotides. Four extensive reviews highlighting various aspects of oligonucleotide chemistry are included. While these articles provide specialists with useful compilations of recent literature, they at the same time should be of considerable general interest, owing to the increasing number of new biological roles discovered for nucleic acids, in particular for RNA, during the past decade. Novel methods for preparation, detection, conjugation and tailoring of nucleic acids are continuously needed to elucidate the multiple biological functions of nucleic acids in more detail and to realize the increased understanding as novel diagnostic and chemotherapeutic approaches. Prof Oretskaya with her co-workers describe how various 2'-functionalized oligonucleotides may be synthesized and how such structurally modified probes bearing a carboxy, carbaldehyde, amino or iodoacetyl group in this particular position may be exploited in studying the recognition of nucleic acids by protein enzymes. The group of Prof Asanuma has designed and synthesized functional oligonucleotides by making use of acyclic non-nucleosidic building blocks that do not retard hybridization and allow construction of photoresponsive and fluorescent probes. The results of these extensive studies are summarized in their review article. N-Alkylated nucleobases play a role in many biological phenomena, the well-known examples being the 5'-terminal cap in mRNA and snRNA and the DNA base modifications as an origin of mutagenesis and chemical carcinogenesis. In addition, alkylated bases are exploited as chemotherapeutics and fluorescent markers. The synthesis and chemical, physical, biological and spectroscopic and properties of N-alkylguanine derivatives, are summarized in an extensive review of Prof Kovacs and his co-workers. Finally, Prof Scrimin et al. critically evaluates the potential and limitations of various multivalent catalysts based on small molecule scaffolds, dendrimers and nanoparticles. The underlying theme is recognition of the prerequisites for cooperativite action of several catalytic functions. This discussion is largely focused on cleavage of phosphate esters, above all the internucleosidic phosphodiester linkages of nucleic acids. I thank all the authors for their thorough work and hope that many organic chemists enjoy reading this issue.