DOCSLIB.ORG

The Citric Acid Cycle

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Citric Acid Cycle Chapter 16 The Citric Acid Cycle: CAC Kreb’s Cycle Tricarboxylic Acid Cycle: TCA The Citric Acid Cycle Key topics: To Know – Also called Tricarboxylic Acid Cycle (TCA) or Krebs Cycle. Three names for the same thing. – Cellular respiration and intermediates for biosynthesis. – Conversion of pyruvate to activated acetate – Reactions of the citric acid cycle – Anaplerotic reactions to regenerate the acceptor – Regulation of the citric acid cycle – Conversion of acetate to carbohydrate precursors in the glyoxylate cycle Discovered CAC in Pigeon Flight Muscle Cellular Respiration • Process in which cells consume O2 and produce CO2 • Provides more energy (ATP) from glucose than Glycolysis • Also captures energy stored in lipids and amino acids • Evolutionary origin: developed about 2.5 billion years ago • Used by animals, plants, and many microorganisms • Occurs in three major stages: - acetyl CoA production (This chapter) - acetyl CoA oxidation (This chapter) - electron transfer and oxidative phosphorylation (Chapter 19) Overall Picture Overall Picture Acetyl-CoA production The area blocked off all occurs in the takes place in the mitochondria. Mitochondrion. So, first pyruvate has to get Acetyl-CoA enters the transported from the CAC. cytoplasm into the mitochondrion. In this Figure, only Glycolysis is in the Cytoplasm. Pyr DH is a Complex Enzyme Pyruvate Dehydrogenase Model TEM Lipoic Acid is linked to a Lys (K) Remember HSCoA ? from Chapter 1 It is down here One Unit of Pyr DH EOC Problem 6: Tests your knowledge of PyrDH. EOC Problem 7: Thiamin deficiency and blood pyruvate. Pyr DH is a Cool Enzyme EOC Problem 5: NAD+ in oxidation and reduction reactions (a through f should be easy). Citrate Synthase Convention to write incoming Acetyl on Top EOC Problem 32, further on the thermodynamics of Citrate Synthase. Aconitase, the Ferris Wheel The Aconitase Iron Sulfur Complex Aconitase has More than One Role Mitochondrial aconitase: Citric Acid Cycle Cytosolic aconitase: 2 roles: 1. citrate isocitrate 2. iron response regulator Aconitase binding iron/RNA To become an iron response regulator, aconitase changes it shape (due to lack of iron) so it can bind RNA. Isocitrate DH ΔGo’ = -21 kJ/mole Mn++ cofactor EOC Problem 8 is all about IsocitDH. αKG DH is Just Like Pyr DH TPP, lipoate FAD Succinyl CoA Synthetase : Substrate Level Phosphorylation One GTP = One ATP Nucleoside diphosphate kinase: GTP + ADP GDP + ATP ΔGo’ = 0 Succinate DH = Old Yellow Malonate was One of the First Competitive Inhibitors Known Fumarase: the addition of water in two parts Don’t Confuse Malate and Maleate Malate DH is Endothermic CAC Energetics Watch Where the Label Goes EOC Problem 18: Labeled glucose carbons and where they go in CAC. Citrate is Prochiral The Acetyl Portion does not get oxidized to CO2 Until the Second Round And it gets randomized at Succinate Energetics of Glycolysis and CAC in ATPs EOC Problems 1 and 2: Balanced equations for Glycolysis and CAC. CAC in Anaerobic Not-Respiratory Organisms It’s a 2 input FORK This is Why OAA D, N, I, K, T, M Anaplerotic Reactions Regulation of CAC EOC Problem 30 and 31 on oxygen and NAD regulation of CAC. Pathway Proteins Form Functional Units but It’s Concentration Dependent Pathways are Protein Modules Flagella LPS Outer Membrane Peptidoglycan ATPase Cytoplasmic Membrane Glycolysis RNA In Animals CAC can not be used for Gluconeogensis from Ac-SCoA D, N, L, K, M, T, I Porphrins: heme (cytochromes, E, Q, P, R hemoglobin), chlorophyll In Bacteria and Plants, Not Vertebrates Overall: 2 Ac-SCoA Succinate Succinate OAA NADH and FADH2 Oxaloacetate CAC Glyoxylate Cycle in Plants in a Membrane Body Linkage to Gluconeogenesis in Plants Regulation Linkage Things to Know and Do Before Class 1. Pyruvate DH…all three parts and cofactors. 2. Chemistry of each step in Citric Acid Cycle. 3. Overall CAC thermodynamics (which steps are at Eq and which are drivers. 4. Prochiral nature of citrate. 5. Amphibolic nature of CAC and why fermenters need almost all of CAC. 6. Importance of anaplerotic reactions and how they work. 7. Glyoxylate Cycle (mammals lack) but plants, some invertebrates and bacteria have it. What does it do? 8. EOC Problems 1-9, 16, 18, 19, 30-32. .
Load more

Recommended publications
  • Citric Acid Cycle
    CHEM464 / Medh, J.D. The Citric Acid Cycle Citric Acid Cycle: Central Role in Catabolism • Stage II of catabolism involves the conversion of carbohydrates, fats and aminoacids into acetylCoA • In aerobic organisms, citric acid cycle makes up the final stage of catabolism when acetyl CoA is completely oxidized to CO2. • Also called Krebs cycle or tricarboxylic acid (TCA) cycle. • It is a central integrative pathway that harvests chemical energy from biological fuel in the form of electrons in NADH and FADH2 (oxidation is loss of electrons). • NADH and FADH2 transfer electrons via the electron transport chain to final electron acceptor, O2, to form H2O. Entry of Pyruvate into the TCA cycle • Pyruvate is formed in the cytosol as a product of glycolysis • For entry into the TCA cycle, it has to be converted to Acetyl CoA. • Oxidation of pyruvate to acetyl CoA is catalyzed by the pyruvate dehydrogenase complex in the mitochondria • Mitochondria consist of inner and outer membranes and the matrix • Enzymes of the PDH complex and the TCA cycle (except succinate dehydrogenase) are in the matrix • Pyruvate translocase is an antiporter present in the inner mitochondrial membrane that allows entry of a molecule of pyruvate in exchange for a hydroxide ion. 1 CHEM464 / Medh, J.D. The Citric Acid Cycle The Pyruvate Dehydrogenase (PDH) complex • The PDH complex consists of 3 enzymes. They are: pyruvate dehydrogenase (E1), Dihydrolipoyl transacetylase (E2) and dihydrolipoyl dehydrogenase (E3). • It has 5 cofactors: CoASH, NAD+, lipoamide, TPP and FAD. CoASH and NAD+ participate stoichiometrically in the reaction, the other 3 cofactors have catalytic functions.
    [Show full text]
  • Eႇects of Alternative Oxidase on Drosophila Under Environmental
    6,1$6$$5, (ႇHFWVRI$OWHUQDWLYH 2[LGDVHRQDrosophila XQGHU(QYLURQPHQWDO6WUHVV 7DPSHUH8QLYHUVLW\'LVVHUWDWLRQV 7DPSHUH8QLYHUVLW\'LVVHUWDWLRQV 6,1$6$$5, (IIHFWVRI$OWHUQDWLYH 2[LGDVHRQDrosophila XQGHU(QYLURQPHQWDO6WUHVV $&$'(0,&',66(57$7,21 7REHSUHVHQWHGZLWKWKHSHUPLVVLRQRI WKH)DFXOW\RI0HGLFLQHDQG+HDOWK7HFKQRORJ\ RI7DPSHUH8QLYHUVLW\ IRUSXEOLFGLVFXVVLRQLQWKHDXGLWRULXP) RIWKH$UYREXLOGLQJ$UYR<OS|QNDWX7DPSHUH RQ2FWREHUDWR¶FORFN $&$'(0,&',66(57$7,21 7DPSHUH8QLYHUVLW\)DFXOW\RI0HGLFLQHDQG+HDOWK7HFKQRORJ\ )LQODQG Responsible 3URIHVVRU+RZDUG7-DFREV supervisor 7DPSHUH8QLYHUVLW\ and Custos )LQODQG Pre-examiners 3URIHVVRU:LOOLDP-%DOODUG 'RFHQW(LMD3LULQHQ 8QLYHUVLW\RI1HZ6RXWK:DOHV 8QLYHUVLW\RI+HOVLQNL $XVWUDOLD )LQODQG Opponent $VVRFLDWH3URIHVVRU9LOOH+LHWDNDQJDV 8QLYHUVLW\RI+HOVLQNL )LQODQG 7KHRULJLQDOLW\RIWKLVWKHVLVKDVEHHQFKHFNHGXVLQJWKH7XUQLWLQ2ULJLQDOLW\&KHFN VHUYLFH &RS\ULJKWDXWKRU &RYHUGHVLJQ5RLKX,QF ,6%1 SULQW ,6%1 SGI ,661 SULQW ,661 SGI KWWSXUQIL851,6%1 3XQD0XVWD2\±<OLRSLVWRSDLQR 7DPSHUH To Pulla iii iv ABSTRACT The mitochondrion is a unique organelle with a central role in energy production and metabolic homeostasis while regulating the life and death of the entire cell. In mitochondrial dysfunction, deficiencies or abnormalities of the mitochondrial oxidative phosphorylation (OXPHOS) system impair cellular energy production. Due to its ability to bypass Complex III and IV of the OXPHOS system and divert electrons from ubiquinol to oxygen, the mitochondrial alternative oxidase (AOX) has drawn attention as a potential
    [Show full text]
  • Lecture 9: Citric Acid Cycle/Fatty Acid Catabolism
    Metabolism Lecture 9 — CITRIC ACID CYCLE/FATTY ACID CATABOLISM — Restricted for students enrolled in MCB102, UC Berkeley, Spring 2008 ONLY Bryan Krantz: University of California, Berkeley MCB 102, Spring 2008, Metabolism Lecture 9 Reading: Ch. 16 & 17 of Principles of Biochemistry, “The Citric Acid Cycle” & “Fatty Acid Catabolism.” Symmetric Citrate. The left and right half are the same, having mirror image acetyl groups (-CH2COOH). Radio-label Experiment. The Krebs Cycle was tested by 14C radio- labeling experiments. In 1941, 14C-Acetyl-CoA was used with normal oxaloacetate, labeling only the right side of drawing. But none of the label was released as CO2. Always the left carboxyl group is instead released as CO2, i.e., that from oxaloacetate. This was interpreted as proof that citrate is not in the 14 cycle at all the labels would have been scrambled, and half of the CO2 would have been C. Prochiral Citrate. In a two-minute thought experiment, Alexander Ogston in 1948 (Nature, 162: 963) argued that citrate has the potential to be treated as chiral. In chemistry, prochiral molecules can be converted from achiral to chiral in a single step. The trick is an asymmetric enzyme surface (i.e. aconitase) can act on citrate as through it were chiral. As a consequence the left and right acetyl groups are not treated equivalently. “On the contrary, it is possible that an asymmetric enzyme which attacks a symmetrical compound can distinguish between its identical groups.” Metabolism Lecture 9 — CITRIC ACID CYCLE/FATTY ACID CATABOLISM — Restricted for students enrolled in MCB102, UC Berkeley, Spring 2008 ONLY [STEP 4] α-Keto Glutarate Dehydrogenase.
    [Show full text]
  • Renal Mitochondrial Cytopathies
    SAGE-Hindawi Access to Research International Journal of Nephrology Volume 2011, Article ID 609213, 10 pages doi:10.4061/2011/609213 Review Article Renal Mitochondrial Cytopathies Francesco Emma,1 Giovanni Montini,2 Leonardo Salviati,3 and Carlo Dionisi-Vici4 1 Division of Nephrology and Dialysis, Department of Nephrology and Urology, Bambino Gesu` Children’s Hospital and Research Institute, piazza Sant’Onofrio 4, 00165 Rome, Italy 2 Nephrology and Dialysis Unit, Pediatric Department, Azienda Ospedaliera di Bologna, 40138 Bologna, Italy 3 Clinical Genetics Unit, Department of Pediatrics, University of Padova, 35128 Padova, Italy 4 Division of Metabolic Diseases, Department of Pediatric Medicine, Bambino Gesu` Children’s Hospital and Research Institute, 00165 Rome, Italy Correspondence should be addressed to Francesco Emma, [email protected] Received 19 April 2011; Accepted 3 June 2011 Academic Editor: Patrick Niaudet Copyright © 2011 Francesco Emma et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Renal diseases in mitochondrial cytopathies are a group of rare diseases that are characterized by frequent multisystemic involvement and extreme variability of phenotype. Most frequently patients present a tubular defect that is consistent with complete De Toni-Debre-Fanconi´ syndrome in most severe forms. More rarely, patients present with chronic tubulointerstitial nephritis, cystic renal diseases, or primary glomerular involvement. In recent years, two clearly defined entities, namely 3243 A > GtRNALEU mutations and coenzyme Q10 biosynthesis defects, have been described. The latter group is particularly important because it represents the only treatable renal mitochondrial defect.
    [Show full text]
  • Mitochondria Targeting As an Effective Strategy for Cancer Therapy
    International Journal of Molecular Sciences Review Mitochondria Targeting as an Effective Strategy for Cancer Therapy Poorva Ghosh , Chantal Vidal, Sanchareeka Dey and Li Zhang * Department of Biological Sciences, the University of Texas at Dallas, Richardson, TX 75080, USA; [email protected] (P.G.); [email protected] (C.V.); [email protected] (S.D.) * Correspondence: [email protected]; Tel.: +972-883-5757 Received: 25 February 2020; Accepted: 6 May 2020; Published: 9 May 2020 Abstract: Mitochondria are well known for their role in ATP production and biosynthesis of macromolecules. Importantly, increasing experimental evidence points to the roles of mitochondrial bioenergetics, dynamics, and signaling in tumorigenesis. Recent studies have shown that many types of cancer cells, including metastatic tumor cells, therapy-resistant tumor cells, and cancer stem cells, are reliant on mitochondrial respiration, and upregulate oxidative phosphorylation (OXPHOS) activity to fuel tumorigenesis. Mitochondrial metabolism is crucial for tumor proliferation, tumor survival, and metastasis. Mitochondrial OXPHOS dependency of cancer has been shown to underlie the development of resistance to chemotherapy and radiotherapy. Furthermore, recent studies have demonstrated that elevated heme synthesis and uptake leads to intensified mitochondrial respiration and ATP generation, thereby promoting tumorigenic functions in non-small cell lung cancer (NSCLC) cells. Also, lowering heme uptake/synthesis inhibits mitochondrial OXPHOS and effectively reduces oxygen consumption, thereby inhibiting cancer cell proliferation, migration, and tumor growth in NSCLC. Besides metabolic changes, mitochondrial dynamics such as fission and fusion are also altered in cancer cells. These alterations render mitochondria a vulnerable target for cancer therapy. This review summarizes recent advances in the understanding of mitochondrial alterations in cancer cells that contribute to tumorigenesis and the development of drug resistance.
    [Show full text]
  • CDC5L Drives FAH Expression to Promote Metabolic Reprogramming in Melanoma
    www.impactjournals.com/oncotarget/ Oncotarget, 2017, Vol. 8, (No. 69), pp: 114328-114343 Research Paper CDC5L drives FAH expression to promote metabolic reprogramming in melanoma Zhichao Gu1, Huafeng Zhang2, Yong Li3, Susu Shen1, Xiaonan Yin4, Wei Zhang1, Ruimin Cheng1, Yong Zhang1, Xiaoyan Zhang1, Hui Chen1, Bo Huang4 and Yuchun Cao1 1Department of Dermatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China 2Department of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China 3Department of Oncology, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, China 4National Key Laboratory of Medical Molecular Biology and Department of Immunology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Beijing 100005, China Correspondence to: Yuchun Cao, email: [email protected] Keywords: fumarylacetoacetate hydrolase (FAH); anaplerotic reactions; cell division cycle 5-like protein (CDC5L); tumor metabolic reprogramming; melanoma Received: August 09, 2017 Accepted: November 15, 2017 Published: December 07, 2017 Copyright: Gu et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License 3.0 (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. ABSTRACT Metabolic reprogramming allows tumor cells to thrive in the typically hypoxic tumor microenvironment. Using immunodetection and clinical data analyses, we demonstrate here that fumarylacetoacetate hydrolase (FAH) is highly expressed in melanoma and correlates with poor survival. FAH knockdown inhibits proliferation and migration, while promoting apoptosis in melanoma cells, result in prolonged survival in tumor-bearing mice.
    [Show full text]
  • Pheochromocytoma: the First Metabolic Endocrine Cancer Ivana Jochmanova1,2 and Karel Pacak1
    CCR FOCUS CCR Focus Pheochromocytoma: The First Metabolic Endocrine Cancer Ivana Jochmanova1,2 and Karel Pacak1 Abstract Dysregulated metabolism is one of the key characteristics of mutations in genes encoding Krebs cycle enzymes or by activation cancer cells. The most prominent alterations are present during of hypoxia signaling. Present metabolic changes are involved in regulation of cell respiration, which leads to a switch from oxidative processes associated with tumorigenesis, invasiveness, metastasis, phosphorylation to aerobic glycolysis. This metabolic shift results and resistance to various cancer therapies. In this review, we discuss in activation of numerous signaling and metabolic pathways the metabolic nature of PHEOs/PGLs and how unveiling the supporting cell proliferation and survival. Recent progress in genet- metabolic disturbances present in tumors could lead to identifica- ics and metabolomics has allowed us to take a closer look at the tion of new biomarkers and personalized cancer therapies. Clin metabolic changes present in pheochromocytomas (PHEO) and Cancer Res; 22(20); 5001–11. Ó2016 AACR. paragangliomas (PGL). These neuroendocrine tumors often exhibit See all articles in this CCR Focus section, "Endocrine Cancers: dysregulation of mitochondrial metabolism, which is driven by Revising Paradigms." Introduction shift in cell metabolism causes cancer cells to present with increased bioenergetics and altered anaplerotic (intermediate Recently, substantial progress has occurred in the understanding replenishing) processes
    [Show full text]
  • Renal Mitochondrial Cytopathies
    SAGE-Hindawi Access to Research International Journal of Nephrology Volume 2011, Article ID 609213, 10 pages doi:10.4061/2011/609213 Review Article Renal Mitochondrial Cytopathies Francesco Emma,1 Giovanni Montini,2 Leonardo Salviati,3 and Carlo Dionisi-Vici4 1 Division of Nephrology and Dialysis, Department of Nephrology and Urology, Bambino Gesu` Children’s Hospital and Research Institute, piazza Sant’Onofrio 4, 00165 Rome, Italy 2 Nephrology and Dialysis Unit, Pediatric Department, Azienda Ospedaliera di Bologna, 40138 Bologna, Italy 3 Clinical Genetics Unit, Department of Pediatrics, University of Padova, 35128 Padova, Italy 4 Division of Metabolic Diseases, Department of Pediatric Medicine, Bambino Gesu` Children’s Hospital and Research Institute, 00165 Rome, Italy Correspondence should be addressed to Francesco Emma, [email protected] Received 19 April 2011; Accepted 3 June 2011 Academic Editor: Patrick Niaudet Copyright © 2011 Francesco Emma et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Renal diseases in mitochondrial cytopathies are a group of rare diseases that are characterized by frequent multisystemic involvement and extreme variability of phenotype. Most frequently patients present a tubular defect that is consistent with complete De Toni-Debre-Fanconi´ syndrome in most severe forms. More rarely, patients present with chronic tubulointerstitial nephritis, cystic renal diseases, or primary glomerular involvement. In recent years, two clearly defined entities, namely 3243 A > GtRNALEU mutations and coenzyme Q10 biosynthesis defects, have been described. The latter group is particularly important because it represents the only treatable renal mitochondrial defect.
    [Show full text]
  • III. Metabolism the Citric Acid Cycle
    Department of Chemistry and Biochemistry Biochemistry 3300 University of Lethbridge III. Metabolism The Citric Acid Cycle Biochemistry 3300 Slide 1 The Eight Steps of the Citric Acid Cycle Enzymes: 4 dehydrogenases (2 decarboxylation) 3 hydration/dehydration 1 substrate level phosphorylation Biochemistry 3300 Slide 2 Overall Reaction (TCA cycle) Overall reaction + Acetyl-CoA + 3NAD + FAD + GDP + Pi 2CO2+ CoA + 3NADH + FADH + GTP Citric acid cycle is central to the energy-yielding metabolism, but it also produces 4- and 5-carbon precursors for other metabolic pathways. Replenishing (anaplerotic) reactions are needed to keep the cycle going! Biochemistry 3300 Slide 3 TCA Cycle – Citrate Synthase Rxn 1 Formation of Citrate by condensation of oxaloacetate and acetyl-CoA, catalyzed by citrate synthase. Citroyl-CoA is formed as an intermediate ∆G'° has to be large to overcome the low oxaloacetate concentration Biochemistry 3300 Slide 4 TCA Cycle – Citrate Synthase Rxn 1 Structure of citrate synthase from G. galus mitochondria Open Closed PDBid 5CTS PDBid 5CSC Oxaloacetate (yellow) binds first and induces large conformational change → creates binding site for Acetyl-CoA Biochemistry 3300 Slide 5 Structure of Citrate Synthase Conformational change upon OAA binding creates Acetyl CoA site Acetyl-CoA Oxaloacetate OAA Ordered sequential mechanism Biochemistry 3300 Slide 6 TCA Cycle – Citrate Synthase Mechanism Rxn 1 Mechanism of citrate synthase reaction (1st step) Formation of Enol Intermediate 1. Biochemistry 3300 Slide 7 TCA Cycle – Citrate Synthase Mechanism Rxn 1 Mechanism of citrate synthase reaction (2nd step) α-keto addition (condensation) 2. Biochemistry 3300 Slide 8 TCA Cycle – Citrate Synthase Mechanism Rxn 1 Mechanism of citrate synthase reaction (3rd step) Thioester hydrolysis Biochemistry 3300 Slide 9 TCA Cycle – Citrate Synthase Mechanism Rxn 1 Mechanism of citrate synthase reaction “Stabilized” enol intermediate of acetyl CoA attacks α-keto group of oxaloacetate.
    [Show full text]
  • Anaplerotic Pathways in Halomonas Elongata: the Role of the Sodium Gradient
    bioRxiv preprint doi: https://doi.org/10.1101/2020.05.13.093179; this version posted May 15, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Anaplerotic pathways in Halomonas elongata: the role of the sodium gradient Karina Hobmeier1;∗ Marie C. Go¨ess1;∗ Christiana Sehr1 Hans J¨orgKunte2 Andreas Kremling1 Katharina Pfl¨uger-Grau1 Alberto Marin-Sanguino1 May 13, 2020 * These two authors contributed equally to the current work. Affiliations: 1 Systems Biotechnology, Technical University of Munich, 85748 Garching, Germany 2 Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Berlin Germany. Abstract Salt tolerance in the γ-proteobacterium Halomonas elongata is linked to its ability to pro- duce the compatible solute ectoine. The metabolism of ectoine production is of great interest since it can shed light on the biochemical basis of halotolerance as well as pave the way for the improvement of the biotechnological production of such compatible solute. The ectoine production pathway uses oxaloacetate as a precursor, thereby connecting ectoine production to the anaplerotic reactions that refill carbon into the TCA cycle. This places a high demand on these reactions and creates the need to regulate them not only in response to growth but also in response to extracellular salt concentration. In this work we combine modeling and ex- periments to analyze how these different needs shape the anaplerotic reactions in H.
    [Show full text]
  • Biochemistry Control of Citric Acid Cycle
    Paper : 04 Metabolism of carbohydrates Module : 14 Control of citric acid cycle Dr. Vijaya Khader Dr. MC Varadaraj Principal Investigator Dr. S. K. Khare, Professor IIT, Delhi. Paper Coordinator Dr. Ramesh Kothari, Professor UGC-CAS Department of Biosciences Saurashtra University, Rajkot-5, Gujarat-INDIA Dr. S. P. Singh Professor Content Reviewer UGC-CAS Department of Biosciences Saurashtra University, Rajkot-5, Gujarat-INDIA Dr. Vikram Raval, Assistant Professor UGC-CAS Department of Biosciences Content Writer Saurashtra University, Rajkot-5 Gujarat-INDIA 1 Metabolism of Carbohydrates Biochemistry Control of citric acid cycle Description of Module Subject Name Biochemistry Paper Name 04: Metabolism of carbohydrates Module 14: Control of citric acid cycle Name/Title 2 Metabolism of Carbohydrates Biochemistry Control of citric acid cycle CONTROL OF CITRIC ACID CYCLE Objectives 1. To understand basis of citric acid cycle (central metabolic hub) 2. Overview of citric acid cycle and enzymes of TCA cycle 3. Various factors affecting citric acid cycle and control points (regulation) 4. Significance of citric acid cycle 5. Anaplerotic reactions 3 Metabolism of Carbohydrates Biochemistry Control of citric acid cycle To understand basis of citric acid cycle (central metabolic hub) The citric acid cycle is the central hub for metabolic pathways. It is popularly known as tricarboxylic acid cycle (TCA cycle) as well as Kreb’s cycle to honour the inventor of this central metabolic path point For your information (FYI): Sir Hans Adolf Krebs (1900-1981) born on August 25th at Hildesheim, Germany was biochemist and physician who pioneered the study of cellular respiration, and energy production. Globally he is acclaimed for his contributions towards 2 of the important biochemical reactions in the body, citric acid cycle and urea cycle.
    [Show full text]
  • Rapid Metabolic and Bioenergetic Adaptations of Astrocytes Under
    Biol. Chem. 2021; 402(9): 1103–1113 Review Marcel Zimmermann* and Andreas S. Reichert* Rapid metabolic and bioenergetic adaptations of astrocytes under hyperammonemia – a novel perspective on hepatic encephalopathy https://doi.org/10.1515/hsz-2021-0172 central nervous system as a consequence of various types Received February 26, 2021; accepted July 18, 2021; of liver dysfunction e.g. cirrhosis, portosystemic shunt, or published online July 30, 2021 blood flow bypassing the liver and thereby mimicking liver failure. The severity of symptoms of HE ranges from Abstract: Hepatic encephalopathy (HE) is a well-studied, mild i.e. confusion or lack of concentration abilities to neurological syndrome caused by liver dysfunctions. very severe such as memory or intellectual impairment, Ammonia, the major toxin during HE pathogenesis, coma, and ultimately death. In principle, HE is distin- impairs many cellular processes within astrocytes. Yet, guished into two forms, minimal or covert HE where no or the molecular mechanisms causing HE are not fully only very mild, often hard to detect symptoms are understood. Here we will recapitulate possible underlying observable, yet the prerequisites of some type of liver mechanisms with a clear focus on studies revealing a link dysfunction to develop HE are met (Zamora Nava and between altered energy metabolism and HE in cellular Delgadillo 2011). Opposed to this, in overt HE symptoms models and in vivo. The role of the mitochondrial glutamate are clearly apparent. Here, certain grades according to the dehydrogenase and its role in metabolic rewiring of the West Haven criteria are distinguished, ranging from TCA cycle will be discussed.
    [Show full text]