Fluorescence and phosphorescence are proving to be extremely sensitive probes for elucidating conformation of proteins and nucleic acids and for studying molecular interactions. Newer instrumentation and techniques hold forth great promise for the future of these luminescence methods in biopolymer research. It must be noted, however, that the discovery that certain amino acids, purines, and pyrimidines emit fluorescence or phosphorescence is relatively recent, occurring within the last decade. Professor Konev is one of the pioneers in the application of these procedures to biopolymers and is highly qualified to write about this subject. This book, though written largely as a monograph of the author's own contributions, is also an excellent review of the subject. Of particular interest are the references to many important Russian papers in this field which have not been recognized in the Western literature. It is apparent from this book that fluorescence and phosphorescence methods are being used about as widely in Russia as elsewhere in the world and that we must not overlook these im- portant contributions. Konev's studies on protein fluorescence have been widely recognized. It is of interest to learn about these and other of his applications. The last part of the book, which deals with fluorescence as a means to probe into the structure and conforma- tion of macromolecules in intact cells, is most interesting. Aside from published symposia this book is the first written specifically about luminescence of biopolymers. Sidney Udenfriend Bethesda. Maryland May, 1967 v CONTENTS Introduction . - - . . . . . . . . . - . . . . . . . . . .