olymerases are the nucleotidyl transferases that are responsible for synthesizing DNA and RNA. They are crucial for essential cellular processes including cellular and viral genome replication, DNA repair and damage tolerance, and transcription. Consistent with their vital roles, polymerases are found in all domains of life. The overall chemistry employed by these enzymes is conserved but there are variations among the different groups of polymerases that confer different substrate specificities and nucleotide incorporation fidelities that allow them to be involved in a wide array of cellular activities. Since polymerases were first isolated more than six decades ago, we have made great progress in understanding how different polymerases have adapted to their specific roles. In this Research Topic we will focus on the enzymatic mechanisms of these enzymes and the relationships between polymerase structure and mechanism, to highlight common themes and unique adaptations.

In recent years many research workers have turned their attention to the quantitative characterization of complex compounds and reactions of complex-formation in solution. Instability constants characterize quantitatively the equili bria in solutions of complex compounds and are extensively used by chemists of widely-varying specialities, in analytical chemistry, electrochemistry, the technology of non-ferrous and rare metals, etc., for calculations of various kinds. Despite the wealth of numerical data, no reasonably full coliection of instability constants of complex compounds has been made until now. The various individual collections of data are far from complete and in most cases omit references to the source materials. Moreover, the present state of the chemistry of complex compounds most urgently demands the complete systematization of data on instability constants and an extension of work in this field which would take advantage of the latest physico-chemical methods. The present work contains instability constants for 1,381 complex compounds. We have considered it convenient to preface the summary of the instability constants with an introductory section of a general theoretical character. This section deals with methods for the calculation of instability constants from experimental data, the influence of external conditions, such as temperature and ionic strength, on the stability of com plexes, and the principal factors determining the stability of complex compounds in aqueous solution. (vii) PREFACE In compiling the summary we have used the original litera ture and abstracts for the most part up to 1954, and some work published in 1955-1956.

DNA polymerases are core tools for molecular biology including PCR, whole genome amplification, DNA sequencing and genotyping. Research has focused on discovery of novel DNA polymerases, characterization of DNA polymerase biochemistry and development of new replication assays. These studies have accelerated DNA polymerase engineering for biotechnology. For example, DNA polymerases have been engineered for increased speed and fidelity in PCR while lowering amplification sequence bias. Inhibitor resistant DNA polymerase variants enable PCR directly from tissue (i.e. blood). Design of DNA polymerases that efficiently incorporate modified nucleotide have been critical for development of next generation DNA sequencing, synthetic biology and other labeling and detection technologies. The Frontiers in Microbiology Research Topic on DNA polymerases in Biotechnology aims to capture current research on DNA polymerases and their use in emerging technologies.

Natural biochemical processes are routinely being discovered in living cells that involve RNA. Some of these processes, such as RNA interference, are now being exploited for biotechnology and medicinal applications. DNA has also proven in recent years to be more than a passive storehouse of information. For example, non-B-form DNA structures formed by G-rich DNA have been shown to participate in the regulation of gene expression, a discovery that presents new possibilities for drug targets in the genome. The current quest to understand how nucleic acid functions at the most fundamental level requires that we have a detailed understanding of nucleic acid-metal ion interactions. Because RNA and DNA are polyanions the structure and biological function of these biopolymers depends strongly on their association with metal ions. While this intimate connection between metal ions and nucleic function has been appreciated for decades, the noncovalent and dynamic nature of these interactions has continually presented challenges to the development of accurate and quantitative descriptions. Over the past few years the development of solution state spectroscopic techniques and the achievement of high resolution X-ray crystal structures have provided tremendous insights into the nature of nucleic acid-metal ion interactions, including direct evidence for their importance in determining nucleic acid structure, from the dictation of folding pathways followed by large RNA molecules to the subtle modulation of DNA groove widths. This new book provides a comprehensive review of the experimental studies that define our current understanding of nucleic acid-metal ion interactions with a particular emphasis being placed on experimental biophysical studies. However, the book is not merely a current review of the literature, as original material and fresh perspectives on published results are also presented. Particularly noteworthy topics include: -The chapter by Williams and fellow workers which reviews information provided by x-ray crystal structures and discusses what this information has revealed about the unique nature of Mg2+ interactions with RNA phosphate groups. The authors provide fresh insights, based upon structural comparisons, for how these interactions govern the local folding pathways of RNA. By dedicating separate chapters to the participation of metal ions in the kinetics and thermodynamics of RNA folding, this volume provides a more in depth treatise of both areas than is typically possible for reviews in which these two related, but distinct, topics are combined -Polyelectrolyte models of nucleic acids have proven to be extremely valuable for understanding the sequestering counterions in a so-called diffuse cloud around polymeric DNA. J. Michael Schurr provides a comprehensive review of polyanion models. Despite the success of polyelectrolyte models in describing some physical properties of nucleic acids, this topic is not always sufficiently understood by many researchers to make use of these models and this chapter serves as a valuable and up to date introduction to this topic. -The chapter by Pizarro and Sadler on metal ion-nucleic acid interactions in disease and medicine is complemented by a chapter by Lippert on coordinative bond formation between metal ions and nucleic acid bases. Together, these two chapters provide an overview of transition metal ion interactions with nucleic acids that illustrates the promise and peril that is associated with direct metal ion coordination to nucleic acid bases in living cells. The book is sufficiently detailed to serve as a reference source for researchers active in the field of nucleic acids biophysics and molecular biology. In addition, chapter authors have added introductory material and enough background material in each chapter so that the book can also can serve as an entry point for students and researchers that have not previously worked in the field which will make the book of lasting value and more accessible by a wider audience.

Viral Replication Enzymes and their Inhibitors, Part B, Volume 50 in The Enzymes series, highlights new advances in the field, with this new volume presenting interesting chapters on a variety of topics surrounding enzymes. - Provides the authority and expertise of leading contributors from an international board of authors - Presents the latest release in The Enzymes series

The "Gold Standard" in Biochemistry text books, Biochemistry 4e, is a modern classic that has been thoroughly revised. Don and Judy Voet explain biochemical concepts while offering a unified presentation of life and its variation through evolution. Incorporates both classical and current research to illustrate the historical source of much of our biochemical knowledge.