Frontmatter -- Preface -- Contents -- List of Contributors -- Significant Steps in the Discovery and Application of Pteridines -- Specific Inhibition of Dihydrofolate Biosynthesis - A New Approach to Chemotherapy -- Mammalian Dihydrofolate Reductase: Porcine Liver Enzyme -- Kinetic Studies of Escherichia Coli Dihydropteroate Synthetase -- Dihydropteroate Synthase: Purification by Affinity Chromatography and Mechanism of Action -- The Properties of Gamma Glutamyl Hydrolase (Conjugase) from Bovine Liver -- The Purification of Riboflavin Synthetase by Affinity Chromatography Using 7-Oxolumazines -- Interaction of Riboflavin Synthetase with Analogues of 6,7-Dimethyl-8-Ribityllumazine -- Structure-Activity Relationship Among Pteridine Derivatives and Related Quinazolines as Inhibitors of Dihydrofolate Reductases -- Spectral Studies of Thymidylate Synthetase -- Four Folate Metabolizing Enzymes of Mouse Embryo Fibroblasts and L-Cells as Tested During the Culture Cycle -- The Activity of the Cobalamine-dependent Methionine- Synthetase (5-Methyl-5, 6, 7, 8-Tetrahydrofolic Acid: Homocysteine Methyltransferase) in Rapidly Growing Human Cells and the Effect of Some Folic Acid Derivatives and Analogues -- The Role of Folate Binding Proteins in Folate Metabolism -- Transport of Folate Compounds into Mammalian and Bacterial Cells -- Transport of Folate Compounds through the Membrane of Human Lymphoblastoid Cells -- The Characterization of High Molecular Weight Complexes of Folic Acid in Mammalian Tissues -- The Enzymic Synthesis of Pterins in Escherichia Coli -- Biosynthesis of Pterins in Mammalian Systems -- The Synthesis of Pterins Catalyzed by Enzymes from Drosophila melanogaster -- Biosynthesis of Biopterin in the Intact Rat and in Mouse Neuroblastoma Cells -- Studies on the Biosynthesis of Riboflavin -- Studies on the Mechanism of Phenylalanine Hydroxylase: Detection of an Intermediate -- Effect of Pteridine Cofactor Structure on the Regulation of Phenylalanine Hydroxylase Activity -- Interrelationships between C-1 Metabolism and Photosynthesis in Euglena Gracilis -- Folate Derivatives and Patterns of C-1 Metabolism in Neurospora Crassa, Wild Type, Ser-1 and Formate Mutants -- The Biosynthesis of Folic Acid and Pteridine Cofactor (s) and its Regulation -- Reduced Pterins as Possible Mediators in Cellular Electron Transfer -- The Handling and Metabolism of Folates in the Rat and Man, with Especial Relationship to Disease -- Red Blood Cell Polyglutamyl Folates in Vitamin B12 Deficiency -- Novel Urinary Metabolites of Folic Acid in the Rat -- "Prune"/"Killer-of-Prune": A Complementary Lethal System in Drosophila Melanogaster Affecting Pteridine Metabolism -- Kynurenine as Trigger in Pterorhodin Synthesis in Ephestia Kuhniella Z. -- Growth Stimulation by 6-Phenacylisoxanthopterin and Related Compounds -- The Possible Role in Gene Regulation of an Isoxanthopterinbinding Protein from Oncopeltus Embryos -- Poly-?-Glutamyl Chain Lengths in some Natural Folates and Contributions of Folic Acid Synthesized by Intestinal Microflora to Rat Nutrition -- Tissue-Specific Synthesis of Methotrexate Polyglutamates in the Rat -- A Convenient Synthesis of Methotrexate and Related Compounds -- Methods for the Synthesis of Folic Acid Analogs, Substituted Folic Acid Analogs, Folic Acid and Folic Acid Conjugates -- New Folate Analogs: Alterations in the C9-N10 Region -- The Synthesis and Study of 10-Thia-10-Deaza-Analogs of Pteroic Acid, Folic Acid, and of Related Compounds: The Problem of Racemization in the Cyclization of Substituted 2-Amino-3-Cyanopyrazines -- Synthesis and Properties of 5-Methyldihydrofolate -- A Coloured Oxidation Product from Tetrahydrofolate -- Pteridine Synthesis -- The 7-Azapteridines -- Enzymatic Oxidation of Pteridin-4-ones and Related Compounds -- Synthesis and Structure of Dihydro- and Tetrahydroderivatives of Pterin 6,7-Dicarboxylic Acid -- Direct Conversion of 4-Hydroxypteridines to their 4-Amino Analogs -- High Pressure Liquid C