The Pentose Phosphate Pathway

ContentsPreface List of Abbreviations 1 Introduction Introduction 2 Formulation of the Pathway Introduction Experiments with Isotopes The L-Type Pathway Other Alternative Formulations of the Pathway D-Erythrose 4-Phosphate as an Intermediate of the Pathway The Transketolase-Transaldolase Coupled Reaction and the Existence of Enzyme Complexes Conclusion 3 Preparation, Properties, and Analysis of the Intermediates of the Pathway Introduction General Analytical Methods Preparation and General Chemistry Individual Intermediates 4 Preparation, Properties, and Analysis of the Enzymes of the Pathway Introduction D-Ribose-5-Phosphate Ketol-Isomerase (EC 5.3.1.6) D-Ribulose-5-Phosphate 3-Epimerase (EC 5.1.3.1) Transaldolase (EC 2.2.1.2) Transketolase (EC 2.2.1.1) Other Enzymes 5 Intermediates in Intact Cells and Tissues Introduction Liver Brain Erythrocytes Other Tissues Ascites and HeLa Cells Bacteria Plants Individual Intermediates 6 Distribution of the Enzymes among Different Tissues and Different Species Introduction General Surveys Specific Tissues Measurements on Other Species Changes in Enzyme Levels during Development Discussion 7 Operation and Regulation in Broken-Cell Preparations Introduction The Utilization of Different Substrates 8 Operation and Regulation in Intact Cells and Tissues Introduction Factors Stimulating the Oxidative Branch of the Pathway The Effects of Changes in Physiological Factors on the Pathway 9 Overall Control of the Pathway Introduction Approach I: Rate-Limiting Enzymes Approach II: Mass Action Ratios Approach III: Cross-Over Plots Approach IV: Enzymes under Hormonal and Allosteric Control Approach V: Enzymes That Change in Response to Changes in the Environment Control of the Oxidative Branch of the Pathway by an Activating Factor Mathematical Models Conclusion 10 Clinical and Nutritional Aspects The Assay of Blood Transketolase Normal Values for Blood Transketolase The "TPP Effect" Measurements of Other Enzymes Clinical Studies of Various Pathological and Physiological States Studies of Transketolase and Thiamine Deficiency in Other Species The Mechanism of Activation of Transketolase by Thiamine 11 Glutathione Metabolism and the Pentose Phosphate Pathway Text 12 Use of Radioisotopes in Elucidating the Nature of and Quantitating the Pentose Pathway Introduction The Nature of the Pathway Quantitation Conclusion References Index