The concept of using photochemical probes in the study of biological systems was developed by Westheimer who published the first photoaffinity labeling experiments more than twenty years ago (J.Bio1. Chem. 237, (1962) 3006). Since then the concept has been used successfully in various areas of biochemistry and recently several new interesting and exciting aspects of the concept have been developed. It is the general opinion by scientists in the "field" that the full potential of photochemical probes in biochemical studies has far from been exploited yet. This is mostly due to the interdisciplinary character of the concept involving photochemistry, synthetic chemistry as well as biochemistry/molecular biology. The perspective of the NATO advanced workshop on "Photochemical Probes in Biochemistry", held in Holte (Copenhagen) Denmark 14-19, August, 1988, was several fold. The workshop was to give an account of the "state of the art" of using photochemical probes in biochemistry as well as to bring together specialists in photochemistry, syn thetic chemistry and molecular biology in order to analyze advantages as well as the inherent problems and pitfalls of the concept and provide suggestions and guidelines for fu ture research. Furthermore, it is the hope of the editor that the present publication which gives an account of the lectures presented at the workshop, will provide an introduction to scientists who are not familiar with photochemical probes, but to whom these could help answer central and pertinent questions.

Fluorescent Probes in Cellular and Molecular Biology presents the most comprehensive evaluation of the theory, instrumentation, and practical applications of fluorescent probes available. It covers basic principles and discusses the use of fluorescent dyes as probes for solvent polarity, solvent viscosity, membrane fluidity, membrane potential, and ionic intracellular composition. This important also describes various applications of fluorescent labels and photolabels, fluorescent analogs, and fluorogenic substrates. No similar publication is devoted exclusively to fluorescent probes, making this an essential guide for anyone working with modern fluorescence techniques. The book is perfect for individuals working in the areas of photochemistry, photobiology, biology, biophysics, or biochemistry. It is also an excellent textbook for graduate students in biology, biophysics, and medicine.

Fluorescence is a very powerful tool for work at the frontier of cell biology, photobiology and bioinstrumentation. The stated aim of the workshop was to highlight the significance of fluorescence work for the understanding of cell and tissue physiology, physiopathology and pharmacology, particulary in terms of the analytical use of fluorescent probes in oncology. In the organization of the workshop a multidisciplinary approach was selected. The purpose of the Advanced Research Workshop (ARW) was to bring together researchers in the various disciplines of tissue optics, imaging, microspectrofluorometry and state of the art probes, in order to explore the full benefits that can be derived in biomedicine through the convergence of these approaches. When applied to in vivo and in situ studies, fluorescence and related optical methods enable us to explore within tissues, cells and organelles photon effects previously understood only in solution photochemistry. Processes which can be studied at the molecular level by photophysics, photochemistry and physical chemistry can be evaluated in living tissue by fluorescence spectroscopy and imaging at the intracellular level in terms of structure and function. Thus, fluorescence adds a new dimension to cell biology and physiology. This approach is now supported by a full and versatile, rapidly growing armamentarium of new selective probes for organelles, enzymes, cations, cytoskeleton and metabolic control.

More than a simple survey of the current literature, Advances in Photochemistry offers critical evaluations written by internationally recognized experts. These pioneering scientists offer unique and varied points of view of the existing data. Their articles are challenging as well as provocative and are intended to stimulate discussion, promote further research, and encourage new developments in the field. This series provides photochemists a forum for critical, authoritative evaluations of advances in every area of photochemistry, including organic, inorganic, and biological topics. Volume 26 continues to report recent advances with a significant, up-to-date selection of papers by internationally recognized researchers. Topics include: Photochemistry of triarylmethane dye leuconitrites. Structure and reactivity of organic intermediates as revealed by time-resolved infrared spectroscopy. Semiconductor photocatalysis for organic synthesis. Photophysical probes of DNA sequence-directed structure and dynamics

Some of the more interesting elements in the chemistry of life are less commonly occuring ones such as nickel and molybdenum. This volume elucidates the chemistry of these elements in important enzymes and also explores the chemistry of elements that do not normally occur in biological molecules, but are useful in probing their structure and function. Topics include: Acquisition and transport of Ni. Mechanistic action of Ni in a wide variety of enzymes. Multielectron redox systems involving pterins in proteins. Chemistry of the pterin and flavin complexes of Mo, Fe, Cu and Ru ions. Replacement of iron in transferrin by a number of other metal ions. Use of polypyridyl complexes of ruthenium and other transition metals as probes of nucleic acid structure through photochemical reactions.