Pyruvate dehydrogenase and the citric acid cycle

Slides:



Advertisements
Similar presentations
Tricarboxylic Acid Cycle
Advertisements

Citric Acid Cycle 1 C483 Spring The net effect of the eight steps of the citric acid cycle is to A) completely oxidize an acetyl group to carbon.
The Citric Acid Cycle II 11/17/2009. The Citric acid cycle It is called the Krebs cycle or the tricarboxylic and is the “hub” of the metabolic system.
KEY CONCEPTS: Section 14-1
CITRIC ACID CYCLE Student Edition 11/8/13 version
12.3 The Citric Acid Cycle Oxidizes AcetylCoA Table 12.2.
Three Fates of Pyruvate Pyruvate  acetyl-CoA Occurs in mitochondria Produce CO 2 and NADH + H + Pyruvate Dehydrogenase Aerobic **Acetyl-CoA used in the.
KREBS CYCLE. Introduction Let us review fates of Pyruvate Depending on the oxidation state of the cell: Aerobic – converted to acetyl-CoA via TCA cycle.
Prentice Hall c2002Chapter 121 Chapter 12 - The Citric Acid Cycle The citric acid cycle is involved in the aerobic catabolism of carbohydrates, lipids.
PYRUVATE DEHYDROGENASE/
1 The Citric Acid Cycle (Tricarboxylic Acid Cyle) 1. The link between gycolysis and citric acid cycle 2. TCA cycle oxidizes 2 –C units 3. Entry and metabolism.
1 24.1The Citric Acid Cycle Chapter 24 Metabolism and Energy Production.
Oxidative Phosphorylation and ATP 24.5 ATP Energy from Glucose Chapter 24 Metabolism and Energy Production.
Dr.S.Chakravarty M.D.. Carbohydrates Fats 36+-/ Proteins recycling.
Gluconeogenesis / TCA 11/12/2009 Gluconeogenesis Gluconeogenesis is the process whereby precursors such as lactate, pyruvate, glycerol, and amino acids.
The Citric acid cycle 4/16/2003
Citric Acid Cycle. General Considerations What is the importance of citric acid cycle? final common pathway for oxidation of fuel molecules provides intermediates.
Aerobic Respiration and Energy Production
Oxidative Decarboxylation of pyruvate and TCA cycle
Metabolism and Energy Production
LEHNINGER PRINCIPLES OF BIOCHEMISTRY Sixth Edition David L. Nelson and Michael M. Cox © 2013 W. H. Freeman and Company CHAPTER 16 The Citric Acid Cycle.
Stages of Metabolism.
TRICARBOXYLIC ACID CYCLE DENTAL BIOCHEMISTRY 2015 LECTURE 12 Michael Lea.
Tricarboxylic Acid Cycle (TCA), Krebs Cycle Occurs totally in mitochondria Pyruvate (actually acetate) from glycolysis is degraded to CO 2 Some ATP is.
Aerobic Metabolism. Summary of Anaerobic Glycolysis Glucose + 2 ADP + 2 P i 2 Lactate + 2 ATP + 2 H 2 O + 2 H +
Oxidative Decarboxylation and Krebs Cycle By Reem M. Sallam, M.D.; Ph.D. Clinical Biochemistry Unit, Pathology Dept. College of Medicine, King Saud University.
CITRIC ACID CYCLE- discovered by Sir Hans Krebs in He was awarded Nobel Prize in Medicine Sir Hans KrebsSir Hans Krebs 1. The citric acid cycle (also.
Chapter 13 - The Citric Acid Cycle The citric acid cycle is involved in the aerobic catabolism of carbohydrates, lipids and amino acids Intermediates of.
SURVEY OF BIOCHEMISTRY Citric Acid Cycle
Glycolysis 1. From glucose to pyruvate; step reactions; 3
INTER 111: Graduate Biochemistry.  To discuss the function of the citric acid cycle in intermediary metabolism, where it occurs in the cell, and how.
Anaerobic metabolism (glycolysis and fermentation) only releases
Oxidative Decarboxylation of Pyruvate
Preparation for the Citric Acid Cycle
Glycolysis Glucose → pyruvate (+ ATP, NADH) Preparatory phase + Payoff phase Enzymes –Highly regulated (eg. PFK-1 inhibited by ATP) –Form multi-enzyme.
Oxidative decarboxylation of pyruvate and Krebs cycle
Harvesting Electrons from the Citric Acid Cycle
Citric Acid Cycle Chapter 19 Stryer Short Course.
Page 584 Glycolysis and TCA cycle: final accounting based on ~2.5 ATP/NADH and 1.5 ATP/FADH2 ~32 ATP/(glucose oxidized to 6CO2) Text – Figures, pg. 584.
The Citric Acid Cycle: Tricarboxylic Acid Cycle Dr. M. Zeeshan Hyder Chapter 17 Biochemistry, Lubert Stryer, 5 th Edition Roundabouts, or traffic circles,
1 Number > Size Macromolecules (10 4 to10 6 ) Small molecules (10 2 to10 4 ) Structure Proteins (ribozymes) Most are heterocyclic organic compounds.
Pyruvate degradation occurs in the mitochondria © Michael Palmer 2014.
Fate of Pyruvate & Citric Acid Cycle
Introduction to the Krebs Cycle Hans Kreb discovered its cyclic nature Goes by three names – Citric acid cycle – Tricarboxylic cycle – Krebs cycle.
Oxidative Decarboxylation of pyruvate and TCA cycle
UNIT II: Bioenergetics and Carbohydrate Metabolism CHAPTER 9: TRICARBOXYLIC ACID CYCLE AND PYRUVATE DEHYDROGENASE COMPLEX.
Chapter 23 Metabolism and Energy Production
Oxidative Decarboxylation of pyruvate and TCA cycle
Oxidative Decarboxylation and Krebs Cycle
FATE OF PYRUVATE OR Pyruvate Metabolism
Chapter 9 Chem 341 Suroviec Fall 2016.
Tricarboxylic Acid Cycle TCA cycle
TRICARBOXYLIC ACID CYCLE (TCA)
Oxidative Decarboxylation and Krebs Cycle
Aerobic Metabolism: The Citric Acid Cycle
THE CITRIC ACID CYCLE The final common pathway for the oxidation of fuel molecules., namely amino acids, fatty acids, and carbohydrates.
Acetyl-CoA and the Citric Acid Cycle
Citric Acid Cycle The citric acid cycle is the final common pathway for the oxidation of carbohydrate, lipid, and protein because glucose, fatty acids,
Matrix Reactions The Fun Begins.
Dr. Sooad Al-Daihan Biochemistry department
Krebs Cycle Tricarboxylic Acid Cycle
Chapter 23 Metabolism and Energy Production
Pyruvate Oxidation and the Citric Acid Cycle
The Citric Acid Cycle Hans Krebs, 1900–1981.
Chapter 10 The Citrate Cycle.
The Krebs Tricarboxylic Acid Cycle
Citric Acid Cycle.
BCM208 Metabolic Biochemistry
TCA Cycle Presented By, Mrs. Lincy Joseph Asst. Prof
Presentation transcript:

Pyruvate dehydrogenase and the citric acid cycle

Pyruvate degradation occurs in the mitochondria

The PDH reaction occurs in three successive steps that are catalyzed by three different subunits

The structural organization of the PDH complex

A lipoamide tether guides the substrate from one active site to the next

The pyruvate dehydrogenase reaction involves multiple coenzymes Subunit Role in catalysis thiamine pyrophosphate E1 provides a carbanion for nucleophilic attack on the substrate lipoamide E2 transfers substrate to coenzyme A, retains hydrogen flavin adenine dinucleotide (FAD) E3 transfers H2 from lipoamide to NAD+

Thiamine pyrophosphate forms a carbanion

Decarboxylation of pyruvate by E1

Release of acetyl-CoA and disposal of hydrogen

Alternate metabolic destinations of pyruvate conversion to acetyl-CoA by PDH for complete degradation or for synthesis of fatty acids and cholesterol carboxylation to oxaloacetate, for use in gluconeogenesis or in the citric acid cycle synthesis of amino acids, e.g., transamination to alanine reduction to lactate

Regulation of PDH by allosteric effectors and by phosphorylation

The overall reaction of the TCA cycle: does it add up?

The citrate synthase reaction

Reactions in the TCA cycle: from citrate to succinyl-CoA

Reactions in the TCA: from succinyl-CoA to oxaloacetate

α-Ketoglutarate dehydrogenase resembles PDH

Regulation of the citric acid cycle ATP and NADH inhibit isocitrate dehydrogenase NADH inhibits α-ketoglutarate dehydrogenase High levels of NADH will lower the oxaloacetate concentration, which limits citrate synthase activity