Lastly, Textbook of biochemistry with Clinical Correlations 4th edition by Thomas L Delvin page no. As we will see later, the same hormones that regulate the rate of glycolysis also regulate gluconeogenesis and the metabolism of glycogen, a stored form of glucose. 274 to 278, Simple and easy to understand, In: Nicolis G, Lefever R (eds) Advances in Chemical Physics. One is the breakdown of glucose while the other is the synthesis of glucose. GLYCOGENOLYSIS & REGULATION OF GLYCOGEN METABOLISM 1. 2019 Oct;15 ... a valuable resource of protein targets of itaconate in macrophages and establishes a negative-feedback link between glycolysis and itaconate, elucidating new functional insights for this anti-inflammatory metabolite. Evidently, it is the most important control point and committed step of glycolysis. CREATE AN ACCOUNT Create Tests & Flashcards. In: Rose AH, Harrison JS (eds) The Yeast, Academic, New York, Hess B, Change B (1959) Naturwissenschaften 46: 238–257, Hess B, Boiteux A (1971) Annu Rev Biochem 40: 237–258, Holzer H, Freytag-Hilf R (1959) Hoppe-Seyler’s Z Physiol Chem 316: 7–30, Hess B, Chance B (1961) J Biol Chem 236: 239–246, Boiteux B, Hess B (1981) Phil Trans R Soc Lond 293: 5–22, Hers H-G, van Schaftingen E (1982) Biochem J 206: 1–12, Evans PR, Farrants GW, Hudson PJ (1981) Phil Trans R Soc Lond 293: 53–62, Hess B, Boiteux A, Busse HG, Gerisch G (1975) Spatiotemporal Organization in Chemical and Cellular Systems. Glycolysis is a vital stage in respiration, as it is the first stage glucose is modified to produce compounds which can go on to be used in the later stages, in addition to generating ATP which can be directly used by the cell. This enzyme prevents the accumulation of glucose 6-phosphate due to product inhibition. Points to remember: Hexokinase is inhibited allosterically by its product, glucose 6-phosphate. Reaction: fructose-1,6-bisphosphate (6C) cleaves into glyceraldehyde-3-phosphate (3C) and dihydroxyacetone phosphate (DHAP) (3C). An independent set of enzymes present in the cytosol carry out glycogenolysis Glycogen is degraded by breaking ɑ-l,4 & ɑ-1,6 … Because of its ubiquity in biology, it is hypothesized that glycolysis was probably one of the earliest metabolic pathways to evolve (… April 1983 in Mosbach/Baden. 1 Sunnybrook Research Institute, Toronto, Canada. It takes place in all the cells of the body. For more information: see Krebs cycle/citric acid cycle/ TCA cycle. These studies led to our current knowledge of the balance between processes of energy generation and energy utilization. Glycolysis is the first metabolic pathway discussed in BIS2A. Springer, Berlin Göttingen Heidelberg, Bücher Th, Rüssmann W (1964) Angew Chem internat Edit 3: 426–439, Plesser Th, Markus M (1982) Hoppe-Seyler’s Z Physiol Chem 363: 546, Max-Planck-Institut für Ernährungsphysiologie, https://doi.org/10.1007/978-3-642-69467-7_15, Colloquium der Gesellschaft für Biologische Chemie 14.–16. Reaction: 3-phosphoglycerate isomerizes to 2-phosphoglycerate. The answer to the question "how does this enzyme sense that ATP is abundant or found in low levels" is that this enzyme has two sites for ATP binding. Glycolysis is a sequence of ten enzyme-catalyzed reactions. Furthermore, fructose 2,6-bisphosphate relieves the inhibitory effe… 108 to 120. Eventually, ATP molecule act as a phosphate donor in this reaction. The reaction catalyzed by PFK is the committed step of glycolysis. While ATP is abundant, both of the places for ATP are occupied and the activity of the enzyme is dra… Basically, glycolysis occurs in the cytosol of all the cells and also known as “Embden-Meyerhof-Parnas pathway“. Glycolysis is the metabolic pathway that converts glucose C 6 H 12 O 6, into pyruvate, CH 3 COCOO − (pyruvic acid), and a hydrogen ion, H +.The free energy released in this process is used to form the high-energy molecules ATP (adenosine triphosphate) and NADH (reduced nicotinamide adenine dinucleotide). Seven healthy male volunteers performed intermittent exercise (15 sec work--15 sec rest) at a high work load for 60 min and six subjects performed continuous exercise at an equally high load to exhaustion, which occurred after 4--6 min. Indeed, glycolysis is an oxygen-independent metabolic pathway. Factors that induce glycolysis repress gluconeogenesis (the reverse of glycolysis) and vice versa because gluconeogenesis is reciprocally regulated. Regulation of glycolysis and gluconeogenesis. Part of Springer Nature. Regulation of Glycolysis by miRNAs in Cancer. Glycolysis is the major pathway for glucose metabolism in which glucose will convert to pyruvate (under aerobic condition) or lactate (anaerobic). 2 moles of ATP will be used in the process, and 4 moles of ATP produced in the subsequent reaction, for a net yield of 2 moles of ATP. Most of the reactions of the glycolytic pathway are reversible, which are also used for. When ATP is low, only one molecule of ATP per enzyme can be linked. REGULATION OF GLYCOLYSIS. Pentose phosphate pathway. Textbook of biochemistry for medical students 7th edition by DM Vasudevan; Chapter 9: Major Metabolic Pathways of Glucose, page no. Gluconeogenesis can be regulated by fructose 1,6-bisphosphatase. The word ‘Glycolysis’, derived from the Greek words, ‘glykys‘ which means sweet; and ‘lysis‘ which means splitting. Points to remember: this reaction is readily reversible. The results indicated that two reactions are of prime importance in the regulation of glycolysis in the working muscle: the formation of glucose-1-P from glycogen and inorganic P through the action of the phosphorylase system and the removal of fructose-6-P through the phosphofructokinase reaction. It provides carbon skeletons for synthesis of non-essential amino acids as well as glycerol part of fat. Conversely, PFK-1 is activated allosterically by high concentrations of AMP, which signal that the cell’s energy stores are depleted. Hence, glycolysis technically means ‘splitting of sugar’ or ‘breakdown of sugar’. Harper’s Illustrated Biochemistry 28th edition; chapter 18: glycolysis and the oxidation of pyruvate, page no. Pyruvate is the end product of aerobic glycolysis whereas lactate will produce under anaerobic glycolysis. The enzyme is inhibited by its product (glucose-6-phosphate). A surplus of ATP allosterically affects PFK-1. Figure 1: Allosteric Regulators of Glycolysis and Gluconeogenesis . High sugar levels stimulate the pancreas to produce insulin, which enhances the entry of glucose into the cell and increases the production of the critical glycolysis enzymes. Firstly, F-1,6-bisP cleaves into two triose phosphate. A study of regulation of glycolysis is directly related to the mechanisms coupling glycolytic reactions to other cellular processes to which glycolysis donates phosphoryl groups, reducing equivalents and carbon fragments for further oxidation, reduction, and biosynthesis. In metabolic pathways, enzymes catalyzing essentially irreversible reactions are potential sites of control. The committed step is the one after which the substrate has only one way to go. Although, it can also proceed under poor oxygen concentration. Glycolysis is both the principal route for glucose metabolism and also the main pathway for the metabolism of fructose, galactose, and other carbohydrates derived from the diet. Regulation of glycolysis in the erythrocyte: role of the lactate/pyruvate and NAD/NADH ratios. Glycolysis is the first step in the breakdown of glucose to extract energy for cellular metabolism. Hence, it is the only pathway that occurs in all cells. Biochemistry : Glycolysis Regulation Study concepts, example questions & explanations for Biochemistry. The committed step of the pathway is defined as the first highly exergonic step that is unique to that pathway. John Wiley 29: 137–168, Boiteux A, Hess B, unpublished experiments, Boiteux A, Hess B, Sel’kov EE (1980) Curr Top Cell Regul 17: 171–203, Hess B (1983) Hoppe-Seyler’s Z Physiol Chem 364: 1–20, Aiuchi T, Daimatsu T, Nakaya K, Nakamura Y (1982) Biochim Biophys Act 685: 289–296, Kuschmitz D, Hess B, unpublished experiments, Goffeau A, Slayman CW (1981) Biochim Biophys Act 639: 197–223, Hess B (1963) In: Karlson P (ed) Funktionelle und morphologische Organisation der Zelle. 2 Department of Surgery, Division of Plastic Surgery, and. It behaves as a negative regulator of the enzyme, in high amounts. It phosphorylates glucose to G6P for ATP production even when blood glucose levels are low. Mechanical regulation of glycolysis via cytoskeleton architecture The mechanics of the cellular microenvironment continuously modulates cell functions such as growth, survival, apoptosis, differentiation and morphogenesis via cytoskeletal remodelling and actomyosin contractility^{1-3… This upregulation of glycolytic enzymes allows for an increased flux though the pathway, and is thus advantageous in maintaining cellular ATP production under hypoxic … Not logged in Additionally, BRS Biochemistry 6th edition, molecular biology, and genetics by Michael A. Lieberman, PhD and Rick Ricer; chapter no. Glycolysis and gluconeogenesis are two pathways of glucose metabolism. Many different oncogenes and tumor suppressor genes are regulated by miRNAs. Thus, the intermediates of glycolysis are useful for the synthesis of amino acids and fat. Regulation of glycolysis and gluconeogenesis. Points to remember: it is an example of substrate-level phosphorylation. Note: page numbers may vary correspondingly upon the edition. Download preview PDF. After that, it will spontaneously isomerize into keto pyruvate, the stable form of pyruvate. Over the years of Warburg’s century, the investigations of metabolic balance and stoichiometries made good use of the various effects which had been observed whenever metabolic states of glycolysis were influenced by oxygen, light, or multiple activators or inhibitors of cellular metabolism. 6 Diagnostic Tests 289 Practice Tests Question of the Day Flashcards Learn by Concept. Glucose transporter-4 (GluT4) transports glucose from the extracellular fluid to muscle cells and adipocytes. The direct consumption and formation of ATP are the same as in anaerobic glycolysis. During this reaction, an aldehyde (glyceraldehyde 3­phosphate) will oxidize to a carboxylic acid with the reduction of NAD+ to NADH. Reaction: glucose-6-phosphate will isomerize to fructose-6-phosphate by phosphohexose isomerase. Glycolysis Regulation It is a general rule of metabolic regulation that pathways are regulated at the first committed step. Therefore, it is most active when glucose-6-phosphate is being rapidly utilized. Overall, when 1 mole of glucose will convert to 2 moles of pyruvate. Glyceraldehyde 3-phosphate and dihydroxyacetone phosphate are interconverted by the enzyme phosphotriose isomerase. Unable to display preview. 18 Dr.Suheir Ereqat 2018/2019 Krebs (citric acid) cycle and oxidative phosphorylation. Meanwhile, two molecules of ATP will form at this stage per molecule of glucose undergoing glycolysis. © 2020 Springer Nature Switzerland AG. Hexokinase Hexokinase is inhibited by glucose 6- phosphate. 6: carbohydrate metabolism. Ongoing aerobic glycolysis requires the oxidation of most of this NADH by the electron transport chain, producing approximately three ATP for each NADH molecule entering the chain. Glycolysis and gluconeogenesis can be regulated by the enzymes and the molecules that help the enzymes in catalyzing the reactions. It comprises ten reactions that occur in the cytoplasm of the cell. The enzyme involved: glyceraldehyde-3-phosphate dehydrogenase. Among other cellular functions, miRNA can regulate metabolic pathways, many of … Hence, this reaction is irreversible. An increase in blood sugar leads to secretion of insulin, which activates phosphoprotein phosphatase I, leading to dephosphorylation and activation of pyruvate kinase. 33. For example, erythrocytes, cornea, lens and regions of the retina. Moreover, glycolysis is a central metabolic pathway with many of its intermediates providing branch point to other pathways. Mn porphyrin regulation of aerobic glycolysis: implications on the activation of diabetogenic immune cells MnP treatment promotes metabolic quiescence, impeding diabetogenic autoimmune responses by restricting the metabolic pathways for energy production and affecting anabolic processes necessary for cell proliferation. It is the most prominent regulatory enzyme in glycolysis. 2. The problem of regulation is therefore related to the mechanisms of coupling: what are the coupling components and how do they interact, what are their stoichiometric relationships, what are the enzymic mechanisms involved, and to what extent do they have controlling functions? Glycolysis consists of an energy-requiring phase followed by an energy-releasing phase. The enzyme involved: phosphoglycerate kinase. This service is more advanced with JavaScript available, Biological Oxidations The enzyme involved: lactate dehydrogenase. The regulatory enzymes or key enzymes of glycolysis are: Hexokinase (glucokinase, in the liver), Phosphofructokinase, and; Pyruvate kinase. Phosphofructokinase: Phosphofructokinase is the most important control element in the glycolytic pathway. Reaction: under anaerobic conditions, pyruvate reduces to lactate. These … PFK is regulated by several factors. Reaction:1,3-Bisphosphoglycerate reacts with ADP to produce 3-phosphoglycerate and ATP. Cite as. The conversion of glucose to pyruvate occurs in broadly two phases: It involves the first four reactions of glycolysis in which intermediates (phosphorylated) synthesized at the expense of ATP. Required fields are marked *, © Copyright 2020 The Virtual Notebook by Zeenat Parveen, STEP 1: Phosphorylation of glucose to glucose-6-phosphate (G6P), STEP 2: Isomerization of G6P to fructose-6-phosphate (F6P), STEP 3: Phosphorylation of F6P to fructose-1,6-bisphosphate (F-1,6-bisP), STEP 4: Cleavage of fructose-1,6-bisphosphate (F-1,6-bisP) to triose phosphate, STEP 5:Oxidation and phosphorylation of glyceraldehyde-3-phosphate to (1,3-BPG), STEP 6: 1,3-BPG converts to 3-phosphoglycerate (3PG), STEP 7: Isomerization of 3PG to 2-phosphoglycerate (2PG), STEP 8: Dehydration of 2PG to phosphoenol pyruvate (PEP), STEP 9: Dephosphorylation of PEP to pyruvate, STEP 10: Reduction of pyruvate to lactate, Product of glycolysis under anaerobic condition, Product of glycolysis under aerobic conditions. In addition, elevated levels of citrate, also inhibit PFK-1. Points to remember: the reaction is reversible. 317 to 327. Humans and other mammals produce the hormone insulin in response to the ingestion of carbohydrates. Reaction: the dehydration of 2-phosphoglycerate results in the formation of phosphoenolpyruvate with the elimination of water molecule. The enzyme involved: phosphohexose isomerase or you can say phosphoglucose isomerase. Glycogenolysis Gandham. 104.248.77.237. Glycolysis is regulated by the concentration of glucose in the blood, the relative concentration of critical enzymes, the competition for the intermediate products of glycolysis and the levels of certain hormones in the bloodstream. Gluconeogenesis closely resembles the reversed pathway of glycolysis, although it is not a complete reversal of glycolysis. ATP is an inhibitor (as well as a substrate!) Once again, the reaction is irreversible. Reaction: fructose-6-phosphate will further phosphorylate to fructose-1,6-bisphosphate. The enzyme involved: phosphoglyceromutase. Glycogenolysis The degradation of stored glycogen in liver & muscle constitutes glycogenolysis The synthesis & degradation of glycogen are not reversible. Video transcript - [Instructor] At its most simplistic level, regulation of metabolic pathways inside of the body is really just a fancy word for a balancing act that's occurring in the body. Next lesson. In such cases, GluT2 is the transporter. Not affiliated Regulation Of Glycolysis And Gluconeogenesis - [Instructor] At its most simplistic level, regulation of metabolic pathways inside of the body is really just a fancy word for a balancing act that's occurring in the body. Glycolysis can be regulated by enzymes such as hexokinase, phosphofructokinase and pyruvate kinase. Certainly, these reactions are the major sites of regulation of glycolysis. • Hormonal regulation of glycolysis ensures coordination among different tissues and organs. Reaction: Glyceraldehyde-3-phosphate oxidizes and simultaneously phosphorylates to 1,3-bisphosphoglycerate (1,3-BPG) with the help of NAD+. This is a preview of subscription content, Racker E (1975) In: Energy transducing mechanisms 3, MTP international review of science, University Park Press, Baltimore pp 163–183, Warburg O, Christian W (1939) Biochem Z 303: 40–68, Lynen F (1941) Justus Liebigs Ann Chem 546: 120–141, Hess B (1973) Organization of glycolysis: Oscillatory and stationary control. If you're seeing this message, it means we're having trouble loading external resources on our website. In glycolysis, the reactions catalyzed by hexokinase, phosphofructokinase, and pyruvate kinase are virtually irreversible; hence, these are the regulatory enzymes in Glycolysis. If you would like to check, see: Glycolysis vs gluconeogenesis. Glycolysis is the only source of energy in cells that lacks mitochondria. Glycolysis is regulated in a reciprocal fashion compared to its corresponding anabolic pathway, gluconeogenesis. Chiefly, glycolysis completes in a series of total of ten steps. Over 10 million scientific documents at your fingertips. Regulation of glycolytic pathway: As described in the previous page and figure 1, glycolysis is regulated by three irreversible enzymes namely: Hexokinase/glucokinase, Phosphofructokinase, and Pyruvate kinase. 3 Department of Immunology, University of Toronto, Toronto, Canada. Points to remember: PFK is an inducible, allosteric and regulatory enzyme. S-glycosylation-based cysteine profiling reveals regulation of glycolysis by itaconate Nat Chem Biol. Your email address will not be published. It is an allosteric enzyme that catalyzes the rate-limiting step. 73 The effects of miRNAs on gene regulation have been reported in the pathogenesis of cancers originating in multiple origins and composed of different cell types.74, 75, 76. Glycolysis can occur as both aerobic and anaerobic depending on the availability of oxygen and the electron transport chain. Any activation of the latter processes will lead to a corresponding and well-balanced activation of glycolysis. Also, this is another example of substrate-level phosphorylation. This translocase is under the influence of insulin. Therefore, fluoride is added to the blood while collecting blood for sugar estimation. There are still many complex areas such as substrate channeling, substrate pooling, enzyme … Rajeev 2. 4 Ross Tilley Burn Centre, … Pyruvate kinase catalyzes an irreversible step and is a regulatoryenzyme of glycolysis. Home Embed All Biochemistry Resources . of PFK. The enzyme involved: hexokinase( in all tissues) and glucokinase (in liver and pancreas). High concentrations of ATP inhibit PKF, thus regulating glycolysis. Points to remember: enolase requires Mg2+ or Mn2+ and if we remove magnesium ions, fluoride will irreversibly inhibit this enzyme. pp 249-266 | After that, DHAP isomerizes into glyceraldehyde-3-phosphate. Thus, fluoride will stop the whole glycolysis. PKF is the enzyme that catalyses the reaction producing fructose 1, 6 phosphate. A major role for insulin in this regulation has been clearly established. Example Questions . In diabetes mellitus, insulin deficiency hinders the entry of glucose into the peripheral cells. Regulation of glycolysis Three regulatory enzymes: Hexokinase & glucokinase Phosphofructokinase Pyruvate kinase Catalysing the irreversible reactions regulate glycolysis. Generally, PFK-1 is inhibited allosterically by elevated levels of ATP, which act as an “energy-rich” signal indicating an abundance of high-energy compounds. Also, Lippincotts illustrated review biochemistry 6th edition; chapter 8: introduction to metabolism and glycolysis page no. Regulation of Glycolysis: The three enzymes namely hexokinase (glucokinase), phosphofructokinase and pyruvate kinase, catalyzing the irreversible reactions regulate glycolysis. In many eukaryotic PFK orthologs, a "side" metabolite of glycolysis, fructose 2,6-bisphosphate, activates the enzyme. This is shown schematically in Fig. glucose + 2NAD+ + 2 Pi + 2 ADP →2pyruvate + 2 NADH + 4 H+ + 2 ATP + 2 H2O. In one cycle, glycolysis yields two molecules of pyruvate, two ATPs, two NADH and two water molecule. try to add very conceptual MCQ’s and their answers at the end, Your email address will not be published. Comparatively, hexokinase has a low Km for glucose (about 0.1 mM). I wrote a separate article on glycolysis vs gluconeogenesis where I discuss similarities and differences between glycolysis and gluconeogenesis. Certainly, these reactions are the major sites of regulation of glycolysis. Insulin does not significantly stimulate the transport of glucose into tissues such as liver, brain, and red blood cells. Essén B, Kaijser L. 1. Reaction: this reaction completes in two steps. Overall, this phase requires two molecules of ATP. Regulation of glycolysis in intermittent exercise in man. 187 to 199. During the first reaction of glycolysis, glucose 6 phosphate is produced. Therefore, it is working near its maximum rate (Vmax), even at fasting blood glucose levels. PFK is also … Although most of the reactions of glycolysis are reversible, three are markedly exothermic and must therefore be considered physiologically irreversible. PFK would seem to be a logical choice for regulation, and indeed PFK displays allosteric regulation. As a result, a high energy phosphate bond will form. Hexokinase/glucokinase: Hexokinase is a ubiquitously expressed enzyme that set the pace of glycolysis. Reciprocal regulation occurs when the same molecule or treatment (phosphorylation, for example) has opposite effects on catabolic and anabolic pathways. This process is experimental and the keywords may be updated as the learning algorithm improves. The enzyme is regulated by … There is no net production or consumption of NADH. This reaction accomplished in two steps. These keywords were added by machine and not by the authors. In addition, Insulin increases its activity whereas glucagon inhibits. The enzyme phosphofructokinase catalyzes the second phosphorylation step of glycolysis using a second molecule of ATP. Points to remember: in aerobic conditions, the pyruvate enters the Krebs cycle for complete oxidation. 2. The enzyme involved: Phosphofructokinase (PFK). Thus, glycolysis is inhibited in the liver but unaffected in muscle when fasting. A study of regulation of glycolysis is directly related to the mechanisms coupling glycolytic reactions to other cellular processes to which glycolysis donates phosphoryl groups, reducing equivalents and carbon fragments for further oxidation, reduction, and biosynthesis. It is activated by fructose 1,6-bisphosphate and inhibited by alanine and by phosphorylation in the liver during fasting when glucagon levels are high. We have provided an overview as to the important areas of regulation of glycolysis, glucose entry, glucose phosphorylation, F-2,6-P 2, and the regulation of glycolytic enzyme gene expression. Basically, it involves the first 3 reactions of the glycolytic cycle and requires two molecules of ATP. Regulation of glycolysis and the Warburg effect in wound healing Roohi Vinaik, 1 Dalia Barayan, 1 Christopher Auger, 1 Abdikarim Abdullahi, 1 and Marc G. Jeschke 1,2,3,4. Points to remember: the reaction is reversible. @article{Tilton1991RegulationOG, title={Regulation of glycolysis in the erythrocyte: role of the lactate/pyruvate and NAD/NADH ratios. Two molecules of NADH are also produced per molecule of glucose. Because glycolytic intermediates feed into several other pathways, the regulation of glycolysis occurs at more than one point. Regulation of Glycolysis Glycolysis operates continuously in most tissues, with a varying rate according to the needs of the cell. Points to remember: pyruvate kinase is a key glycolytic enzyme and it is the third irreversible reaction. If not, glucose is metabolized by the blood cells, so that lower blood sugar values are obtained. This is the currently selected item. The regulatory enzymes or key enzymes of glycolysis are: Although most of the reactions of glycolysis are reversible, three are markedly exothermic and must therefore be considered physiologically irreversible. Firstly, PEP converts into enol pyruvate intermediate. Reaction: glucose phosphorylates to glucose-6-phosphate in the presence of hexokinase which splits the ATP into ADP. Any activation of the latter processes will lead to a corresponding and well-balanced activation of glycolysis. Moreover, it is a pathway through which the largest flux of carbon occurs in most cells. Anaerobic glycolysis takes place in erythrocytes, cornea, lens and regions of the retina. 32. Thus up to this point, we get two molecules of glyceraldehyde-3-phosphate from one molecule of glucose at the expense of 2 ATP molecules. Also, anaerobic glycolysis forms the major source of energy for muscles when there is a lack or insufficient amount of oxygen is present. In this article, we will look at the steps of glycolysis, its relation to other pathways and clinical conditions related to glycolysis. The remaining reactions will come under this phase in which a net of two molecules of ATP will form by substrate-level phosphorylation per glucose molecule metabolized. Afterwards, Pyruvate can be completely oxidized to CO2 and H2O by enzymes present in the mitochondria. Phosphofructokinase (PKF) is a key enzyme in the regulation of glycolysis. The allosteric regulation of glycolysis under hypoxic conditions is subsequently followed by the transcriptional upregulation of glucose transporters and glycolytic enzymes by the hypoxia inducible factor (HIF) transcription factor. In: Rate control of biological processes, Cambridge pp 105–131, Sols A, Gancedo C, DelaFuente G (1971) Energy-Yielding Metabolism in Yeasts. Glucokinase Glucokinase, which specifically … Corpus ID: 25460617. Points to remember: the reaction is reversible and the product contains a high energy bond. High concentrations of this molecule signal that a cell no longer requires glucose for energy. 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