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Is Glucose A Substrate Or Product

Glucose As A Substrate In Recombinant Strain Fermentation Technology

Glucose As A Substrate In Recombinant Strain Fermentation Technology

, Volume 31, Issue2 , pp 163167 | Cite as Glucose as a substrate in recombinant strain fermentation technology By-product formation, degradation and intracellular accumulation of recombinant protein Glucose supplements to complex growth media of Escherichia coli affect the production of a recombinant model protein under the control of a temperature-sensitive expression system. The bacterial Crabtree effect, which occurs in the presence of glucose under aerobic conditions, not only represses the formation of citric acid cycle enzymes, but also represses the formation of the plasmid-encoded product even though the synthesis of this protein is under the control of the temperature-inducible lambda PR-promoter/cl857-repressor expression system. When the recombinant E. coli is grown at a moderate temperature (35 C) with protein hydrolysate and glucose as substrates, a biphasic growth and production pattern is observed. In the first phase, the cells grow with a high specific growth rate, utilizing glucose and forming glutamate as a byproduct. The intracellular level of recombinant protein is very low in this phase. Later, glutamate is consumed, indicating an active citric acid cycle. The degradation of glutamate is accompanied by the intracellular accumulation of high amounts of recombinant protein. FermentationGlutamateRecombinant ProteinSpecific Growth RateRecombinant Strain These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves. This is a preview of subscription content, log in to check access. Unable to display preview. Download preview PDF. Amarasingham CR, Bernhard DD (1965) Regulation of 2-ketoglutarate dehydrogenase formation in Escherichia coli. J Biol Chem 240:36643 Continue reading >>

Molecular Biology: Enzymes And Metabolism

Molecular Biology: Enzymes And Metabolism

Molecular Biology: Enzymes and Metabolism Function of enzymes in catalyzing biological reactions Enzymes are catalysts, which are things that increase the rate of a reaction, but does not get used up during the reaction. Structure determines function. A change in structure => a change in function. Important biological reactions catalyzed by enzymes: Enzymes decrease the activation energy (Ea) of a reaction by lowering the energy of the transition state. Enzymes increase the rate of a reaction by decreasing the activation energy. Enzymes will increase the rate constant, k, for the equation rate = k[A][B]. Enzymes do NOT change the Keq of a reaction. Enzymes do not change Keq because it lowers the activation energy for BOTH forward and reverse reactions. Enzymes will make the reverse reaction go faster also. Enzymes do not change G, the net change in free energy. Enzymes affect the kinetics of a reaction, but not the thermodynamics. Enzyme-substrate interactions occur at the enzyme's active site. Enzyme-substrate specificity derives from structural interactions. Lock and key model: rigid active site. Substrate fits inside the rigid active site like a key. Induced fit model: flexible active site. Substrate fits inside the flexible active site, which is then induced to "grasp" the substrate in a better fit. Enzymes can be specific enough to distinguish between stereoisomers. Almost all enzymes in your body is made of protein. The most important RNA enzyme in your body is the ribosome. Primary: this is the sequence of the protein or RNA chain. Secondary: this is hydrogen bonding between the protein backbone. Examples include alpha helices and beta sheets (backbone H-bonding). For RNA, this is base pairing. Tertiary: this is the 3-D structure of the enzyme. This involves -R Continue reading >>

Oxidation Of Pyruvate And The Citric Acid Cycle

Oxidation Of Pyruvate And The Citric Acid Cycle

Breakdown of Pyruvate After glycolysis, pyruvate is converted into acetyl CoA in order to enter the citric acid cycle. Key Takeaways In the conversion of pyruvate to acetyl CoA, each pyruvate molecule loses one carbon atom with the release of carbon dioxide. During the breakdown of pyruvate, electrons are transferred to NAD+ to produce NADH, which will be used by the cell to produce ATP. In the final step of the breakdown of pyruvate, an acetyl group is transferred to Coenzyme A to produce acetyl CoA. acetyl CoA: a molecule that conveys the carbon atoms from glycolysis (pyruvate) to the citric acid cycle to be oxidized for energy production Breakdown of Pyruvate In order for pyruvate, the product of glycolysis, to enter the next pathway, it must undergo several changes to become acetyl Coenzyme A (acetyl CoA). Acetyl CoA is a molecule that is further converted to oxaloacetate, which enters the citric acid cycle (Krebs cycle). The conversion of pyruvate to acetyl CoA is a three-step process. Step 1. A carboxyl group is removed from pyruvate, releasing a molecule of carbon dioxide into the surrounding medium. (Note: carbon dioxide is one carbon attached to two oxygen atoms and is one of the major end products of cellular respiration. ) The result of this step is a two-carbon hydroxyethyl group bound to the enzyme pyruvate dehydrogenase; the lost carbon dioxide is the first of the six carbons from the original glucose molecule to be removed. This step proceeds twice for every molecule of glucose metabolized (remember: there are two pyruvate molecules produced at the end of glycolysis); thus, two of the six carbons will have been removed at the end of both of these steps. Step 2. The hydroxyethyl group is oxidized to an acetyl group, and the electrons are picked up by NAD+, Continue reading >>

Cellular Respiration And Photosynthesis

Cellular Respiration And Photosynthesis

Big Ideas Cellular Respiration and Photosynthesis Cellular respiration is the process by which the chemical energy of "food" molecules is released and partially captured in the form of ATP. Carbohydrates, fats, and proteins can all be used as fuels in cellular respiration, but glucose is most commonly used as an example to examine the reactions and pathways involved. In glycolysis, the 6-carbon sugar, glucose, is broken down into two molecules of a 3-carbon molecule called pyruvate. This change is accompanied by a net gain of 2 ATP molecules and 2 NADH molecules. The Krebs (or Citric Acid) cycle occurs in the mitochondria matrix and generates a pool of chemical energy (ATP, NADH, and FADH 2 ) from the oxidation of pyruvate, the end product of glycolysis. Pyruvate is transported into the mitochondria and loses carbon dioxide to form acetyl-CoA, a 2-carbon molecule. When acetyl-CoA is oxidized to carbon dioxide in the Krebs cycle, chemical energy is released and captured in the form of NADH, FADH 2 , and ATP. The electron transport chain allows the release of the large amount of chemical energy stored in reduced NAD + (NADH) and reduced FAD (FADH 2 ). The energy released is captured in the form of ATP (3 ATP per NADH and 2 ATP per FADH 2 ). The electron transport chain (ETC) consists of a series of molecules, mostly proteins, embedded in the inner mitochondrial membrane. The glucose required for cellular respiration is produced by plants. Plants go through a process known as photosynthesis. Photosynthesis can be thought of as the opposite process of cellular respiration. Through two processes known as the light reactions and the dark reactions, plants have the ability to absorb and utilize the energy in sunlight. This energy is then converted along with water and carbon d Continue reading >>

Substrate And Product Inhibition On Yeast Performance In Ethanol Fermentation

Substrate And Product Inhibition On Yeast Performance In Ethanol Fermentation

Substrate and Product Inhibition on Yeast Performance in Ethanol Fermentation School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China Program in Environment and Ecology, Faculty of Science and Engineering, Meisei University, 2-1-1, Hodokubo, Hino, Tokyo 1918506, Japan *Phone: 86-21-54744540. E-mail: [emailprotected] . Cite this: Energy Fuels 2015, 29, 2, 1019-1027 Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days. Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts. The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. A batch fermentation utilizing Saccharomyces cerevisiae BY4742 was conducted to determine the inhibitory effects of highly concentrated substrate and product levels on yeast. Experiments were performed to determine the largest dosage of substrate and the largest product concentration that the yeast could tolerate in a very high gravity fermentation process. The yeasts growth and fermentation activities were characterized by changes in the biomass and ethanol yield under different substrate and product concentrations during fermentation. All of the experiments were performed at a pH of 5.0 and a t Continue reading >>

Bbc Bitesize - Higher Biology - Cellular Respiration - Revision 2

Bbc Bitesize - Higher Biology - Cellular Respiration - Revision 2

Cellular respiration refers to the breakdown of glucose and other respiratory substrates to make energy carrying molecules called ATP. Metabolic pathways of respiration making ATP The main substrate within the respiration pathway is glucose. The metabolic pathway involved in respiration can be split into three main parts: Citric acid cycle - occurs in the matrix of the mitochondria Electron transport chain - occurs in the inner membrane of the mitochondria. Glycolysis is the breakdown of glucose into two pyruvate molecules. This process does not require oxygen (it is anaerobic). The production of pyruvate from glucose involves the production of several intermediate molecules. Phosphorylation of some of these intermediates requires two ATP molecules in an energy investment stage. Four ATP molecules are then regenerated in the production of other intermediates. This breakdown of glucose into pyruvate therefore results in a net gain of two ATP molecules. Dehydrogenase enzymes remove electrons from the intermediates and these electrons are transferred to the coenzymes NAD forming NADH. These coenzymes take the electrons to the inner membrane of the mitochondria for use in the electron transport chain. If oxygen is available, pyruvate molecules progress into the citric acid cycle. If oxygen is not available then pyruvate undergoes fermentation. Alcoholic fermentation - ethanol and CO2 is produced. This occurs in plants and fungi. Lactic acid fermentation - lactic acid is produced. This occurs in animals. Continue reading >>

Section 16.1oxidation Of Glucose And Fatty Acids To Co2

Section 16.1oxidation Of Glucose And Fatty Acids To Co2

The complete aerobic oxidation of glucose is coupled to the synthesis of as many as 36 molecules of ATP: Glycolysis, the initial stage of glucose metabolism, takes place in the cytosol and does not involve molecular O. It produces a small amount of ATP and the three-carbon compound pyruvate. In aerobic cells, pyruvate formed in glycolysis is transported into the mitochondria, where it is oxidized by O to CO. Via chemiosmotic coupling, the oxidation of pyruvate in the mitochondria generates the bulk of the ATP produced during the conversion of glucose to CO. In this section, we discuss the biochemical pathways that oxidize glucose and fatty acids to CO and HO; the fate of the released electrons is described in the next section. Go to: Cytosolic Enzymes Convert Glucose to Pyruvate A set of 10 enzymes catalyze the reactions, constituting the glycolytic pathway, that degrade one molecule of glucose to two molecules of pyruvate (Figure 16-3). All the metabolic intermediates between glucose and pyruvate are watersoluble phosphorylated compounds. Four molecules of ATP are formed from ADP in glycolysis (reactions 6 and 9). However, two ATP molecules are consumed during earlier steps of this pathway: the first by the addition of a phosphate residue to glucose in the reaction catalyzed by hexokinase (reaction 1), and the second by the addition of a second phosphate to fructose 6-phosphate in the reaction catalyzed by phosphofructokinase-1 (reaction 3). Thus there is a net gain of two ATP molecules. The balanced chemical equation for the conversion of glucose to pyruvate shows that four hydrogen atoms (four protons and four electrons) are also formed: (For convenience, we show pyruvate in its un-ionized form, pyruvic acid, although at physiological pH it would be largely dissociat Continue reading >>

Glycolysis

Glycolysis

Suppose that we gave one molecule of glucose to you and one molecule of glucose to Lactobacillus acidophilus—the friendly bacterium that turns milk into yogurt. What would you and the bacterium do with your respective glucose molecules? Glycolysis is a series of reactions that and extract energy from glucose by splitting it into two three-carbon molecules called pyruvates. Glycolysis is an ancient metabolic pathway, meaning that it evolved long ago, and it is found in the great majority of organisms alive today​. In organisms that perform cellular respiration, glycolysis is the first stage of this process. However, glycolysis doesn’t require oxygen, and many anaerobic organisms—organisms that do not use oxygen—also have this pathway. Glycolysis has ten steps, and depending on your interests—and the classes you’re taking—you may want to know the details of all of them. However, you may also be looking for a greatest hits version of glycolysis, something that highlights the key steps and principles without tracing the fate of every single atom. Let’s start with a simplified version of the pathway that does just that. Glycolysis takes place in the cytosol of a cell, and it can be broken down into two main phases: the energy-requiring phase, above the dotted line in the image below, and the energy-releasing phase, below the dotted line. Energy investment phase. Glucose is first converted to fructose-1,6-bisphosphate in a series of steps that use up two ATP. Then, unstable fructose-1,6-bisphosphate splits in two, forming two three-carbon molecules called DHAP and glyceraldehyde-3-phosphae. Glyceraldehyde-3-phosphate can continue with the next steps of the pathway, and DHAP can be readily converted into glyceraldehyde-3-phosphate. Energy payoff phase. In a s Continue reading >>

Glycolysis

Glycolysis

Glucose G6P F6P F1,6BP GADP DHAP 1,3BPG 3PG 2PG PEP Pyruvate HK PGI PFK ALDO TPI GAPDH PGK PGM ENO PK Glycolysis The metabolic pathway of glycolysis converts glucose to pyruvate by via a series of intermediate metabolites. Each chemical modification (red box) is performed by a different enzyme. Steps 1 and 3 consume ATP (blue) and steps 7 and 10 produce ATP (yellow). Since steps 6-10 occur twice per glucose molecule, this leads to a net production of ATP. Summary of aerobic respiration Glycolysis (from glycose, an older term[1] for glucose + -lysis degradation) is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + 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).[2][3] Glycolysis is a determined sequence of ten enzyme-catalyzed reactions. The intermediates provide entry points to glycolysis. For example, most monosaccharides, such as fructose and galactose, can be converted to one of these intermediates. The intermediates may also be directly useful. For example, the intermediate dihydroxyacetone phosphate (DHAP) is a source of the glycerol that combines with fatty acids to form fat. Glycolysis is an oxygen independent metabolic pathway, meaning that it does not use molecular oxygen (i.e. atmospheric oxygen) for any of its reactions. However the products of glycolysis (pyruvate and NADH + H+) are sometimes metabolized using atmospheric oxygen.[4] When molecular oxygen is used for the metabolism of the products of glycolysis the process is usually referred to as aerobic, whereas if no oxygen is used the process is said to be anaerobic.[5] Thus, glycolysis occurs, with variations, in nearly all organisms, both aerobic and a Continue reading >>

Cellular Respiration Module

Cellular Respiration Module

For one glucose molecule that has moved through glycolysis, the preparatory step and the Krebs cycle, answer the following questions: 1. How many ATP have been generated so far? ______________ 4. How many CO2 molecules have been produced? Electrons from glycolysis, the prep-step and the Krebs cycle are carried in NADH and FADH2 to the ETS. Electron Transport System (ETS) or Chain (ETC) The ETS is a series of electron carriers on the cristae of inner membrane of mitochondria The NADH and FADH2 bind to proteins in the ETS and the electrons that they are carrying are transferred to the ETS. The protons are released as H+. Proton pumps (using the energy from the electrons) move the H+ from the matrix to intermembrane space, creating a high concentration of H+ in the intermembrane space Electrons lose their energy as they move down the ETS (driving the H+ pumps). At the end of the ETS, two low-energy electrons along with two H+ bind to oxygen (1/2 of an O2 molecule), the final electron acceptor, forming H2O. There is a higher concentration of H+ in intermembrane space of mitochondria than in the matrix. H+ flows down its concentration gradient toward the matrix providing energy. H+ moves through the ATP synthase enzyme. As H+ moves down its gradient from the intermembrane space to the matrix, ATP synthase (in cristae) adds phosphate to ADP producing ATP (ADP + P --> ATP). Continue reading >>

Biochemistry, Glycolysis

Biochemistry, Glycolysis

2 Department of Orthopaedic Surgery, University of Kentucky School of Medicine Glycolysis is ametabolic pathwayand an anaerobic source of energy that has evolved in nearly all types of organisms. The process entails the oxidation of glucose molecules, the single most important organic fuel in plants, mirobes, and animals. Most cells prefer glucose (there are exceptions, such as acetic acid bacteria which preferethanol). In glycolysis, per molecule of glucose, 2 ATP moleculesare utilized, while 4 ATP, 2 NADH, and2 pyruvates are produced. The pyruvate can be used in the citric acid cycle, or serve as a precursor for other reactions. [1] [2] [3] Glucose is a hexose sugar, which means that it is a monosaccharide with 6 carbon atoms and 6 oxygen atoms. The first carbon consists of an aldehyde group, and the other 5 carbons have 1 hydroxyl group each. In glycolysis, glucose is broken down ultimately into pyruvate and energy, a total of2 ATP, is derived in the process (Glucose + 2 NAD+ + 2 ADP + 2 Pi --> 2 Pyruvate + 2 NADH + 2 H+ + 2 ATP + 2 H2O). The hydroxyl groups allow for phosphorylation. The specific form of glucose used in glycolysis is glucose 6-phosphate. Glucokinase is a subtype of hexokinase found in humans.Glucokinase has a lower affinity for glucose and is found only in the pancreas and liver, whereas hexokinase is found in all cells. Glycolysis occurs in the cytosol of the cell. It is metabolic pathway which creates ATP without the use of oxygen but can occur in the presence of oxygenas well. In cells which use aerobic respiration as the primary source of energy, the pyruvate formed from the pathway can be used in the citric acid cycle and go through oxidative phosphorylation to be oxidized into carbon dioxide and water. Even if cells primarily use oxidative ph Continue reading >>

Glycolysis

Glycolysis

Importance of Glycolysis Glycolysis is the first step in the breakdown of glucose to extract energy for cellular metabolism. Learning Objectives Explain the importance of glycolysis to cells Key Takeaways Key Points Glycolysis is present in nearly all living organisms. Glucose is the source of almost all energy used by cells. Overall, glycolysis produces two pyruvate molecules, a net gain of two ATP molecules, and two NADH molecules. Key Terms glycolysis: the cellular metabolic pathway of the simple sugar glucose to yield pyruvic acid and ATP as an energy source heterotroph: an organism that requires an external supply of energy in the form of food, as it cannot synthesize its own Nearly all of the energy used by living cells comes to them from the energy in the bonds of the sugar glucose. Glucose enters heterotrophic cells in two ways. One method is through secondary active transport in which the transport takes place against the glucose concentration gradient. The other mechanism uses a group of integral proteins called GLUT proteins, also known as glucose transporter proteins. These transporters assist in the facilitated diffusion of glucose. Glycolysis is the first pathway used in the breakdown of glucose to extract energy. It takes place in the cytoplasm of both prokaryotic and eukaryotic cells. It was probably one of the earliest metabolic pathways to evolve since it is used by nearly all of the organisms on earth. The process does not use oxygen and is, therefore, anaerobic. Glycolysis is the first of the main metabolic pathways of cellular respiration to produce energy in the form of ATP. Through two distinct phases, the six-carbon ring of glucose is cleaved into two three-carbon sugars of pyruvate through a series of enzymatic reactions. The first phase of glyc Continue reading >>

Glycolysis Regulation

Glycolysis Regulation

It is a general rule of metabolic regulation that pathways are regulated at the first committed step. The committed step is the one after which the substrate has only one way to go. Because glycolytic intermediates feed into several other pathways, the regulation of glycolysis occurs at more than one point. This allows the regulation of several pathways to be coordinated. For example, dihydroxyacetone phosphate is the precursor to the glycerol component of lipids. An animal in a well‐fed state synthesizes fat and stores it for energy. Glycerol is needed for formation of triglycerides, even though ATP synthesis is less important. Metabolic control must therefore allow glucose to be converted into triose even though the complete breakdown of the trioses to CO 2 need not occur at such a high rate. The free energy diagram of glycolysis shown in Figure points to the three steps where regulation occurs. Remember that for any reaction, the free energy change depends on two factors: the free energy difference between the products and reactants in the standard state and the concentration of the products and reactants. In the figure, the standard free energies and the concentrations were used to compute the total free energy differences between products and reactants at each step. Reactions at equilibrium have a free energy change of zero. Remember that at equilibrium the rates of forward and reverse reactions are equal. Therefore, the conversion of, for example, 3‐ phosphoglycerate to glyceraldehyde‐3‐phosphate occurs rapidly. In contrast, the reactions far from equilibrium, such as the conversion of phosphoenol pyruvate to pyruvate, have rates that are greater in the forward than in the reverse direction. Imagine a series of pools in a fountain. If two pools are at the Continue reading >>

Substrate-level Phosphorylation

Substrate-level Phosphorylation

This article has multiple issues. Please help improve it or discuss these issues on the talk page . This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed. This article may be confusing or unclear to readers. Please help us clarify the article . There might be a discussion about this on the talk page . ( Learn how and when to remove this template message ) Substrate-level phosphorylation exemplified with the conversion of ADP to ATP Substrate-level phosphorylation is a metabolic reaction that results in the formation of ATP or GTP by the direct transfer of a phosphoryl (PO3) group to ADP or GDP from another phosphorylated compound. Unlike oxidative phosphorylation , oxidation and phosphorylation are not coupled in the process of substrate-level phosphorylation, and reactive intermediates are most often gained in the course of oxidation processes in catabolism . Most ATP is generated by oxidative phosphorylation in aerobic or anaerobic respiration while substrate-level phosphorylation provides a quicker, less efficient source of ATP, independent of external electron acceptors . This is the case in human erythrocytes , which have no mitochondria, and in oxygen-depleted muscle. Substrate-level phosphorylation occurs in the cytoplasm of cells during glycolysis and in mitochondria during the Krebs cycle under both aerobic and anaerobic conditions. In the pay-off phase of glycolysis , a net of 2 ATP are produced by substrate-level phosphorylation. The first substrate-level phosphorylation occurs after the conversion of 3-phosphoglyceraldehyde and Pi and NAD+ to 1,3-bisphosphoglycerate via glyceraldehyde 3-phosphate dehydrogenase . 1,3-bisphosphoglyc Continue reading >>

24.2 Carbohydrate Metabolism Anatomy And Physiology

24.2 Carbohydrate Metabolism Anatomy And Physiology

By the end of this section, you will be able to: Describe the pathway of a pyruvate molecule through the Krebs cycle Explain the transport of electrons through the electron transport chain Describe the process of ATP production through oxidative phosphorylation Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen atoms. The family of carbohydrates includes both simple and complex sugars. Glucose and fructose are examples of simple sugars, and starch, glycogen, and cellulose are all examples of complex sugars. The complex sugars are also called polysaccharides and are made of multiple monosaccharide molecules. Polysaccharides serve as energy storage (e.g., starch and glycogen) and as structural components (e.g., chitin in insects and cellulose in plants). During digestion, carbohydrates are broken down into simple, soluble sugars that can be transported across the intestinal wall into the circulatory system to be transported throughout the body. Carbohydrate digestion begins in the mouth with the action of salivary amylase on starches and ends with monosaccharides being absorbed across the epithelium of the small intestine. Once the absorbed monosaccharides are transported to the tissues, the process of cellular respiration begins ( Figure 1 ). This section will focus first on glycolysis, a process where the monosaccharide glucose is oxidized, releasing the energy stored in its bonds to produce ATP. Figure 1. Cellular Respiration. Cellular respiration oxidizes glucose molecules through glycolysis, the Krebs cycle, and oxidative phosphorylation to produce ATP. Glucose is the bodys most readily available source of energy. After digestive processes break polysaccharides down into monosaccharides, including glucose, the monosaccharides are transporte Continue reading >>

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