PNA: a universal tool in molecular biology: Peptide Nucleic Acids: Protocols and Applications edited by P.E. Nielsen and M. Egholm

Abstract

1999, Horizon Scientific Press. UK£59.99 hbk (x+266 pages)ISBN 1 898 48616 6This book is an upgraded guide to the properties and possibilities of the DNA mimic peptide nucleic acid (PNA), which is more complete than the ‘Users guide’ found on the PerSeptive Biosystems homepage, even though it has been recently revised (http://www.pebio.com/ds/pna/users.html). As stated in the preface, the focus of this book is on the actual applications and protocols relating to PNA. The neutrality of the backbone and the flexibility of adding functional units to the PNA oligonucleotide make it a formidable tool, and its wide range of applications are well illustrated in the spectrum of protocols included in the book.The introduction gives the reader a good overview of the properties of the PNA molecule, as well as some of its drawbacks (e.g. the solubility problem of purine-rich sequences). The subsequent chapters cover the synthesis of PNA and different PNA hybrids. They illustrate the development in the efforts being made to synthesize PNA in order for it to be as readily achievable as nucleic acid synthesis. The reader is given good, solid advice when it comes to the type of linker that should be used for the different types of PNA–DNA hybrids.Some aspects of the radiolabeling of PNA molecules by using protein-specific enzymes are discussed, as well as the possibilities of using the free amino-terminus for fluorescence labeling. Some of the applications reflect the thermodynamic properties of PNA, and this is exemplified in Chapter 3.1 by Holmen and Norden.The use of PNA as a probe for hybridization in different detection systems is clearly illustrated in Chapter 3.2. In addition, PNA-assisted rare cleavage is a good illustration of what PNA can be used for with regard to blocking enzyme function. The PNA–DNA–PNA hybrid shields the DNA site from methylases and therefore a non-methylated site can be created, making the targeted sequence sensitive to restriction-enzyme cleavage after PNA removal. The labeling of plasmids with different types of fluorescent molecules, such as rhodamine, has long been a problem if one has needed to combine this with expression from a reporter gene in the plasmid. Philip Felgner and his colleagues (Chapter 4.5) have solved this by using a specifically engineered site in the reporter plasmids, enabling a PNA clamp to bind to the plasmid. The clamp is labeled either with a fluorescent label or with biotin. This technique has made it possible to track the fate of plasmids in the cells at the same time as maintaining gene expression.In conclusion, this book is a necessary requirement for anyone wanting to delve into the field of PNA. It will also be an aid to developing the new genetic tool that PNA represents, thus enabling researchers to create new solutions to problems in nucleic acid detection and gene medicine.