TAILIEUCHUNG - Lecture Biochemistry (2/e): Chapter 20 - Reginald Garrett, Charles Grisham

The glycolytic pathway converts glucose to pyruvate and produces two molecules of ATP per glucose only a small fraction of the potential energy available from glucose. Under anaerobic conditions, pyruvate is reduced to lactate in animals and to ethanol in yeast, and much of the potential energy of the glucose molecule remains untapped. In the presence of oxygen, however, a much more interesting and thermodynamically complete story unfolds. | Chapter 20 The Tricarboxylic Acid Cycle to accompany Biochemistry, 2/e by Reginald Garrett and Charles Grisham All rights reserved. Requests for permission to make copies of any part of the work should be mailed to: Permissions Department, Harcourt Brace & Company, 6277 Sea Harbor Drive, Orlando, Florida 32887-6777 Outline Bridging Step - Pyruvate Decarboxylase Entry - Citrate Synthase - All the Other Steps Intermediates for Other Pathways Anaplerotic Reactions Regulation of the TCA Cycle The Glyoxylate Cycle The TCA Cycle aka Citric Acid Cycle, Krebs Cycle Pyruvate (actually acetate) from glycolysis is degraded to CO2 Some ATP is produced More NADH is made NADH goes on to make more ATP in electron transport and oxidative phosphorylation The Chemical Logic of TCA Understand this! TCA seems like a complicated way to oxidize acetate units to CO2 But normal ways to cleave C-C bonds and oxidize don't work for CO2: cleavage between Cs and to a carbonyl an -cleavage of an -hydroxyketone The Chemical Logic of TCA A better way to cleave acetate. Better to condense acetate with oxaloacetate and carry out a -cleavage - TCA combines this with oxidation to form CO2, regenerate oxaloacetate and capture all the energy as NADH and ATP! Entry into the TCA Cycle Pyruvate dehydrogenase and citrate synthase Pyruvate is oxidatively decarboxylated to form acetyl-CoA Pyruvate dehydrogenase uses TPP, CoASH, lipoic acid, FAD and NAD+ Citrate synthase is classic CoA chemistry! Know both mechanisms NADH & succinyl-CoA are allosteric inhibitors Note (Table ) that CS has large, neg G! Aconitase Isomerization of Citrate to Isocitrate Citrate is a poor substrate for oxidation So aconitase isomerizes citrate to yield isocitrate which has a secondary -OH, which can be oxidized Note the stereochemistry of the Rxn: aconitase removes the pro-R H of the pro-R arm of citrate! Aconitase uses an iron-sulfur cluster - see Fig. .

• Sinh học
• Lecture Biochemistry
• Biological phenomena
• Living systems
• Structure of cells
• Tricarboxylic acid cycle
• Anaplerotic reactions
• Principles of biochemistry
• Lecture Principles of biochemistry
• Biological systems
• Biochemical compounds
• Biological macromolecules
• Chemical principles
• Properties of water
• Hydrogen bonding
• Amino acids
• Amino acid structure
• Protein purification
• Cell extract
• Protein classification
• Protein 3 Dimensional structure
• Protein folding
• Protein 3 D structure
• 3 D structure
• Oxygen binding curve
• Enzyme kinetics
• Rate constants
• Catalytic Power
• Classes of enzymes
• Inhibitor kinetics
• Enzyme regulation
• Allosteric regulation
• Enzyme action
• Mechanisms of enzyme action
• Ions Cofactors
• Metal ion
• Nguyên lý hóa sinh
• Biotin cofactor
• Conformation of monosaccharides
• Carbohydrate classifications
• Oligo carbohydrate
• Polysaccharides carbohydrate
• Lipid subclasses
• Acyl lipids
• Fluid mosaic model
• membrane transporters
• Metabolism proceed
• Anaeorbic process
• Triose Phosphate Isomerase
• Regulation of glycolysis
• Control points in glycolysis
• Citric acid cycle
• TCA cycle
• Additional pathways
• Carbohydrate metabolism
• Electron transport
• Chemosmotic theory