Nucleic Acids, Protein Synthesis, and Coenzymes: Volume IV

As components of all biological systems, purines and pyrimidines have drawn the attention of biological chemists for nearly 200 years, beginning with the discovery of uric acid by Scheele (7), through the isolation of nucleic acids by Miescher (2) and Kossel (3), the recognition of nucleotides as coenzymes and metabolic intermediates, and leading to our present knowledge of the genetic and chemical properties of nucleic acids and the role of nucleotides in metabolic regulation. A natural part of the interest in these compounds has been concerned with their metabolism-biosynthesis, degradation, and interrelationships with other cellular processes. These studies have in large part achieved their present success through application of the powerful techniques of modern biochemistry: isolation of discrete enzyme systems, use of isotopic tracers, chromatography, and biochemical genetics. When the chapter on this topic was prepared for the previous edition of Metabolic Pathways, the individual steps in the synthesis and degradation of purines and pyrimidines compounds had been established. Other summaries have appeared describing techniques for the isolation and assay of the intermediates and enzymes involved (4), Recent developments in this area of metabolism have centered about questions of metabolic control and enzymology. This chapter will reflect the emphasis on these topics.