Preface [Hot topic: DNA Chemistry (Guest Editor: Zvi Kelman)]

In this issue of Current Organic Chemistry there are papers describing different aspects of nucleic acid chemistry and metabolism. Histones, the building blocks of nucleosomes and a major component of chromatin, play essential roles in the eukaryotic cell. One of their roles is to regulate transcription by participating in forming repressive chromatin structures. In the last several years it has become apparent that histones undergo a large number of post-translational modifications prior to heterochromatin (transcriptionally repressed) formation. The first contribution, by David Donze (Louisiana State University, Louisiana, USA), describes many of the histone modifications and their roles in transcription. The second contribution is by David Frick (New York Medical College, New York, USA), and describes the enzymes needed for Hepatitis C Virus (HCV) replication. HCV is a cause of contagious hepatitis and presents a major threat to human health. To date, however, no vaccine or effective treatment is available. Recent studies on viral replication machinery and the structure and function of the replication proteins may provide clues for future therapeutic targets. One of the emerging approaches to study the thermodynamic properties of protein-nucleic acid and protein-nucleotide interactions is the use of isothermal titration microcalorimetry (ITC). The third paper, by Magnus Stödeman (Center for Chemistry and Chemical Engineering, Lund, Sweden), describes the technique and summarizes many recent studies. The last contribution is by Hans-Achim Wagenknecht (Technical University Munich, Garching, Germany) and provides an overview of synthesis methods for the production of labeled systems used in the study of charge transfer and migration process in DNA, drawing from published techniques spanning over the past decade. A consensus opinion of the reductive electron transfer mechanism is also offered, summarizing current and accepted mechanistic details of the charge transfer process. I would like to thank all the authors for their efforts in making this issue interesting and informative. As the field is rapidly expanding, we welcome your suggestions for topics to be covered in future issues.