1 / 22

Chapter 13

Chapter 13. Chem 341 Suroviec Fall 2013. I. Overview. Glycolysis co n verts to two C 3 units. The free energy released in this process is harvested to synthesize ATP from ADP and P i. I. Overview. Some pathways are irreversible. Catabolic and anabolic pathways MUST differ.

grazia
Download Presentation

Chapter 13

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 13 Chem 341 Suroviec Fall 2013

  2. I. Overview • Glycolysis converts to two C3 units. The free energy released in this process is harvested to synthesize ATP from ADP and Pi

  3. I. Overview • Some pathways are irreversible • Catabolic and anabolic pathways MUST differ C. Every metabolic pathway has a 1st committed step

  4. II. Glucose A. Glucose • 6 carbon sugar with aldehyde group •  form: OH group of the anomeric C is on OPPOSITE side of ring from CH2OH •  form: OH group of the anomeric C is on SAME side of ring from CH2OH

  5. II. Glucose C. Glycogenolysis • Only liver can make glucose available to the liver at large

  6. III. Glycolysis • Stage I. Energy investment • Glucose is phosphorylated and cleaved • Uses 2 ATP • Stage II. Energy recovery • 2 molecules of glyceraldehyde-3-phosphate converted to pyruvate • Produces 4 ATP

  7. Hexokinase Metabolically irreversible reaction IV. Reactions of Glycolysis

  8. Conversion of G6P to F6P B. Phosphoglucose Isomerase

  9. PFK phosphorylates FBP Operates similar to hexokinase C. Phosphofrutokinase • Tetrameric enzyme • R and T states in equilibrium • ATP is both a substrate and and allosteric inhibitor

  10. Each PFK has 2 binding site Substrate site Inhibitor site Inhibitor site binds ATP only in T state Shifts equilibrium in favor of T at high ATP concentrations C. PFK

  11. Catalyzes cleavage of FBP to form GAP and DHAP D. Aldolase

  12. GAP continues down the glycolytic pathway DHAP and GAP are ketose-aldose isomers Final reaction Stage I E. Triose Phosphate Isomerase

  13. Exergonic reaction Synthesis of high energy 1,3-BPG F. Glyceraldehyde-3-Phosphate Dehydrogenase

  14. G. Phosphoglycerate Kinase • Bilobal with Mg2+ • 1,3-BPG common intermediate whose consumption pulls reaction forward

  15. 3PG is converted to 2PG Phosphorylated His is needed to complete reaction 2,3-BPG allosteric inhibitor of deoxyhemoglobin H. Phosphoglycerate Mutase

  16. 2PG dehydrated to PEP Needs Mg2+ F- inhibitor of reaction I. Enolase

  17. PEP is cleaved via PK to form pyruvate Forms ATP Step 1: ADP nucleophilically attacks the PEP, forms ATP Step 2: Enolpyruvate tautomerizes to pyruvate J. Pyruvate Kinase

  18. ATP Investment of 2 ATP per glucose Generation of 4 ATP NADH Glucose oxidized 2 NAD+ reduced to NADH Electron transport Pyruvate 2 molecules are produced Complete oxidation to CO2 done in citric acid cycle 3 products of glycolysis

  19. Pyruvate Aerobic conditions completely oxidized to CO2 and H2O Anaerobic conditions converted to reduced end product to reoxidize NADH III. Fermentation

  20. Demand for ATP high Supply of oxygen is low A. Homolactic Fermentation

  21. Forms CO2, ethanol and NAD+ TPP is essential cofactor of pyruvate decarboxylase B. Alcoholic Fermentation

  22. Glycolysis operates continuously in most tissues Flux must vary to meet needs How do we determine to flux control mechanisms? IV. Control of Glycolysis • One 3 reactions of glycolysis potentially control it: • Hexokinase • Phosphofrucokinase • Pyrivate kinase

More Related