Introduction: Bioinorganic enzymology II.

To contribute to the research and teaching pedagogics of the multidisciplinary subject that is Bioinorganic Chemistryalso denoted as Inorganic Biochemistry or Metallobiochemistry we organized and served as coeditors of two thematic issues. The first of these, now designated Bioinorganic Enzymology I (Volume 96, Number 7, 1996; Figure 1, left), contains a detailed account of the structural and functional aspects of enzyme sites as they were understood at the time, includes electron transfer with and without enzymatic catalysis, and describes selected enzyme systems implicated in hydrogen, carbon, oxygen, and nitrogen metabolism. The second issue, Biomimetic Inorganic Chemistry (Volume 104, Number 2, 2004; Figure 1, middle) recognizes the essential role of abiological systems in interpreting the structure and function of native sites. The principal components of such systems are designed molecular representations of these sites and are often termed models or synthetic analogues. This issue largely deals with ligand design and implementation, the classic systems of iron−sulfur clusters, heme-dioxygen and electron-transfer centers (Fe, Cu), and nonredox (Zn) and redox-active (V, Mn, Fe, Cu, Mo) site analogues. Over the nearly twenty-year period encompassed by the two thematic issues, but especially in the past decade, bioinorganic chemistry as a discipline has evolved an identity that does not merely maintain the currency of earlier subjects but expands the field well beyond the purview of the preceding issues. Consequently, we have organized a third thematic issue, Bioinorganic Enzymology II (Figure 1, right), to summarize certain consequential advances whose origins can be found in the five significant areas of investigation emphasized on the front cover. As will become evident, the contents of this issue subsume a broader array of subjects than the title implies. Enzymology continues to refine known catalytic mechanisms and reveal new ones for investigation. Molecular biology presents an array of powerful experimental methodologies applicable to proteins and nucleic acids. Among these, site-directed protein variants are particularly incisive in bioinorganic research. Inorganic synthesis is the foundation of biomimetic inorganic chemistry. Spectroscopy and associated magnetism investigations define ground and excited electronic states, details of chemical bonding including bond covalency and pathways of electron transfer, and magnetic coupling of metal sites. Computational methods provide geometrical and electronic metal site structures, approximate global protein architecture, and formulate reaction coordinates. Superimposed on these endeavors are the structural insights gained from continually expanding crystallographic databases, including protein structures at atomic resolution. Results from all of these subjects lead to a molecular level understanding of function as detailed in Bioinorganic Enzymology II. In addition, contributions in the burgeoning fields of metalloimaging, medicinal inorganic chemistry, and metallosensors are included. It is anticipated that Bioinorganic Enzymology II will contribute significantly to the foundation for future studies in this rapidly evolving and expanding field. With the publication of Bioinorganic Enzymology II, appearing consecutively in two parts (issues 7 and 8), the triad of issues under our joint guest editorship is complete. We trust that the latest addition and its predecessors provide a useful resource in the teaching and research of bioinorganic chemistry. We acknowledge the editorial support of Chemical Reviews and are much indebted to all authors for their authoritative and scholarly contributions, without which this series would not have been possible.