CAS Number: 50-99-7
EC Number: 200-075-1
Chemical formula: C6H12O6
Molar mass: 180.156 g/mol
Glucose is the main type of sugar in the blood and is the major source of energy for the body's cells.
Glucose comes from the foods we eat or the body can make it from other substances.
Glucose is carried to the cells through the bloodstream.
Several hormones, including insulin, control glucose levels in the blood.
Glucose is a simple sugar with the molecular formula C6H12O6.
Glucose is the most abundant monosaccharide, a subcategory of carbohydrates.
Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using energy from sunlight, where it is used to make cellulose in cell walls, the most abundant carbohydrate in the world.
Glucose can exist in both a straight-chain and ring form.
Glucose open-chain form of glucose makes up less than 0.02% of the glucose molecules in an aqueous solution.
Glucose rest is one of two cyclic hemiacetal forms.
In its open-chain form, the glucose molecule has an open (as opposed to cyclic) unbranched backbone of six carbon atoms, where C-1 is part of an aldehyde group (C=O)−.
Therefore, glucose is also classified as an aldose, or an aldohexose.
The aldehyde group makes glucose a reducing sugar giving a positive reaction with the Fehling test.
Glucose metabolism and various forms of it in the process
Glucose-containing compounds and isomeric forms are digested and taken up by the body in the intestines, including starch, glycogen, disaccharides and monosaccharides.
Glucose is stored in mainly the liver and muscles as glycogen.
Glucose is distributed and used in tissues as free glucose.
Main articles: Glycolysis and Pentose phosphate pathway
In humans, glucose is metabolised by glycolysis and the pentose phosphate pathway.
Glycolysis is used by all living organisms,: 551 with small variations, and all organisms generate energy from the breakdown of monosaccharides.
Glucose the further course of the metabolism, it can be completely degraded via oxidative decarboxylation, the citric acid cycle (synonym Krebs cycle) and the respiratory chain to water and carbon dioxide.
Glucose there is not enough oxygen available for this, the glucose degradation in animals occurs anaerobic to lactate via lactic acid fermentation and releases less energy.
Muscular lactate enters the liver through the bloodstream in mammals, where gluconeogenesis occurs (Cori cycle).
With a high supply of glucose, the metabolite acetyl-CoA from the Krebs cycle can also be used for fatty acid synthesis.
Glucose is also used to replenish the body's glycogen stores, which are mainly found in liver and skeletal muscle. These processes are hormonally regulated.
In energy metabolism, glucose is the most important source of energy in all organisms.
Glucose for metabolism is stored as a polymer, in plants mainly as starch and amylopectin, and in animals as glycogen.
Glucose circulates in the blood of animals as blood sugar.
The naturally occurring form of glucose is d-glucose, while l-glucose is produced synthetically in comparatively small amounts and is of lesser importance[citation needed].
Glucose is a monosaccharide containing six carbon atoms and an aldehyde group, and is therefore an aldohexose.
The glucose molecule can exist in an open-chain (acyclic) as well as ring (cyclic) form.
Glucose is naturally occurring and is found in its free state in fruits and other parts of plants.
Glucose animals, glucose is released from the breakdown of glycogen in a process known as glycogenolysis.
Glucose, as intravenous sugar solution, is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system.
Glucose is also on the list in combination with sodium chloride.
Glucose is produced by plants through the photosynthesis using sunlight, water and carbon dioxide and can be used by all living organisms as an energy and carbon source.
However, most glucose does not occur in its free form, but in the form of its polymers, i.e. lactose, sucrose, starch and others which are energy reserve substances, and cellulose and chitin, which are components of the cell wall in plants or fungi and arthropods, respectively.
These polymers, when consumed by animals, fungi and bacteria, are degraded to glucose using enzymes.
All animals are also able to produce glucose themselves from certain precursors as the need arises.
Neurons, cells of the renal medulla and erythrocytes depend on glucose for their energy production.
In adult humans, there are about 18 g of glucose, of which about 4 g are present in the blood.
Approximately 180 to 220 g of glucose are produced in the liver of an adult in 24 hours.
Many of the long-term complications of diabetes (e.g., blindness, kidney failure, and peripheral neuropathy) are probably due to the glycation of proteins or lipids. In contrast, enzyme-regulated addition of sugars to protein is called glycosylation and is essential for the function of many proteins.
Uptake
Ingested glucose initially binds to the receptor for sweet taste on the tongue in humans.
Glucose complex of the proteins T1R2 and T1R3 makes it possible to identify glucose-containing food sources.
Glucose mainly comes from food—about 300 g per day are produced by conversion of food,but it is also synthesized from other metabolites in the body's cells.
In humans, the breakdown of glucose-containing polysaccharides happens in part already during chewing by means of amylase, which is contained in saliva, as well as by maltase, lactase, and sucrase on the brush border of the small intestine.
Glucose is a building block of many carbohydrates and can be split off from them using certain enzymes.
Glucosidases, a subgroup of the glycosidases, first catalyze the hydrolysis of long-chain glucose-containing polysaccharides, removing terminal glucose.
In turn, disaccharides are mostly degraded by specific glycosidases to glucose.
Glucose names of the degrading enzymes are often derived from the particular poly- and disaccharide; inter alia, for the degradation of polysaccharide chains there are amylases (named after amylose, a component of starch), cellulases (named after cellulose), chitinases (named after chitin), and more.
Furthermore, for the cleavage of disaccharides, there are maltase, lactase, sucrase, trehalase, and others. In humans, about 70 genes are known that code for glycosidases.
They have functions in the digestion and degradation of glycogen, sphingolipids, mucopolysaccharides, and poly(ADP-ribose).
Humans do not produce cellulases, chitinases, or trehalases, but the bacteria in the gut flora do.
Glucoseorder to get into or out of cell membranes of cells and membranes of cell compartments, glucose requires special transport proteins from the major facilitator superfamily.
Glucose the small intestine (more precisely, in the jejunum),glucose is taken up into the intestinal epithelium with the help of glucose transporters via a secondary active transport mechanism called sodium ion-glucose symport via sodium/glucose cotransporter 1 (SGLT1).
Further transfer occurs on the basolateral side of the intestinal epithelial cells via the glucose transporter GLUT2,as well uptake into liver cells, kidney cells, cells of the islets of Langerhans, neurons, astrocytes, and tanycytes.
Glucose enters the liver via the portal vein and is stored there as a cellular glycogen.
Glucose the liver cell, it is phosphorylated by glucokinase at position 6 to form glucose 6-phosphate, which cannot leave the cell.
Glucose 6-phosphatase can convert glucose 6-phosphate back into glucose exclusively in the liver, so the body can maintain a sufficient blood glucose concentration.
Glucose other cells, uptake happens by passive transport through one of the 14 GLUT proteins.
Glucose the other cell types, phosphorylation occurs through a hexokinase, whereupon glucose can no longer diffuse out of the cell.
The glucose transporter GLUT1 is produced by most cell types and is of particular importance for nerve cells and pancreatic β-cells. GLUT3 is highly expressed in nerve cells.
Glucose from the bloodstream is taken up by GLUT4 from muscle cells (of the skeletal muscle and heart muscle) and fat cells.GLUT14 is expressed exclusively in testicles.
Excess glucose is broken down and converted into fatty acids, which are stored as triglycerides.
Glucose the kidneys, glucose in the urine is absorbed via SGLT1 and SGLT2 in the apical cell membranes and transmitted via GLUT2 in the basolateral cell membranes.
About 90% of kidney glucose reabsorption is via SGLT2 and about 3% via SGLT1.
Biosynthesis
Main articles: Gluconeogenesis and Glycogenolysis
In plants and some prokaryotes, glucose is a product of photosynthesis.
Glucose is also formed by the breakdown of polymeric forms of glucose like glycogen (in animals and mushrooms) or starch (in plants).
The cleavage of glycogen is termed glycogenolysis, the cleavage of starch is called starch degradation.
Glucose metabolic pathway that begins with molecules containing two to four carbon atoms (C) and ends in the glucose molecule containing six carbon atoms is called gluconeogenesis and occurs in all living organisms.
The smaller starting materials are the result of other metabolic pathways.
Ultimately almost all biomolecules come from the assimilation of carbon dioxide in plants during photosynthesis:
The free energy of formation of α-d-glucose is 917.2 kilojoules per mole: 59 In humans, gluconeogenesis occurs in the liver and kidney,but also in other cell types.
Glucose the liver about 150 g of glycogen are stored, in skeletal muscle about 250 g.
However, the glucose released in muscle cells upon cleavage of the glycogen can not be delivered to the circulation because glucose is phosphorylated by the hexokinase, and a glucose-6-phosphatase is not expressed to remove the phosphate group.
Unlike for glucose, there is no transport protein for glucose-6-phosphate.
Gluconeogenesis allows the organism to build up glucose from other metabolites, including lactate or certain amino acids, while consuming energy.
The renal tubular cells can also produce glucose.
Glucose also can be found outside of living organisms in the ambient environment.
Glucose concentrations in the atmosphere are detected via collection of samples by aircraft and are known to vary from location to location.
For example, glucose concentrations in atmospheric air from inland China range from 0.8-20.1 pg/l, whereas east coastal China glucose concentrations range from 10.3-142 pg/l.
Glucose degradation
Glucose other living organisms, other forms of fermentation can occur.
The bacterium Escherichia coli can grow on nutrient media containing glucose as the sole carbon source:
Glucose some bacteria and, in modified form, also in archaea, glucose is degraded via the Entner-Doudoroff pathway.
Use of glucose as an energy source in cells is by either aerobic respiration, anaerobic respiration, or fermentation.
Glucose first step of glycolysis is the phosphorylation of glucose by a hexokinase to form glucose 6-phosphate.
Glucose main reason for the immediate phosphorylation of glucose is to prevent its diffusion out of the cell as the charged phosphate group prevents glucose 6-phosphate from easily crossing the cell membrane.
Furthermore, addition of the high-energy phosphate group activates glucose for subsequent breakdown in later steps of glycolysis.
At physiological conditions, this initial reaction is irreversible.
In anaerobic respiration, one glucose molecule produces a net gain of two ATP molecules (four ATP molecules are produced during glycolysis through substrate-level phosphorylation, but two are required by enzymes used during the process).
In aerobic respiration, a molecule of glucose is much more profitable in that a maximum net production of 30 or 32 ATP molecules (depending on the organism) through oxidative phosphorylation is generated.
Click on genes, proteins and metabolites below to link to respective articles.
Tumor cells often grow comparatively quickly and consume an above-average amount of glucose by glycolysis,which leads to the formation of lactate, the end product of fermentation in mammals, even in the presence of oxygen.
Glucose effect is called the Warburg effect. For the increased uptake of glucose in tumors various SGLT and GLUT are overly produced.
In yeast, ethanol is fermented at high glucose concentrations, even in the presence of oxygen (which normally leads to respiration but not to fermentation).
Glucose effect is called the Crabtree effect.
Glucose can also degrade to form carbon dioxide through abiotic means.
This has been demonstrated to occur experimentally via oxidation and hydrolysis at 22˚C and a pH of 2.5.
Energy source
Diagram showing the possible intermediates in glucose degradation; Metabolic pathways orange: glycolysis, green: Entner-Doudoroff pathway, phosphorylating, yellow: Entner-Doudoroff pathway, non-phosphorylating
Glucose is a ubiquitous fuel in biology.
Glucose is used as an energy source in organisms, from bacteria to humans, through either aerobic respiration, anaerobic respiration (in bacteria), or fermentation.
Glucose is the human body's key source of energy, through aerobic respiration, providing about 3.75 kilocalories (16 kilojoules) of food energy per gram.
Breakdown of carbohydrates (e.g., starch) yields mono- and disaccharides, most of which is glucose.
Through glycolysis and later in the reactions of the citric acid cycle and oxidative phosphorylation, glucose is oxidized to eventually form carbon dioxide and water, yielding energy mostly in the form of ATP.
Glucose insulin reaction, and other mechanisms, regulate the concentration of glucose in the blood.
Glucose physiological caloric value of glucose, depending on the source, is 16.2 kilojoules per gram and 15.7 kJ/g (3.74 kcal/g), respectively.
Glucose high availability of carbohydrates from plant biomass has led to a variety of methods during evolution, especially in microorganisms, to utilize the energy and carbon storage glucose.
Differences exist in which end product can no longer be used for energy production.
The presence of individual genes, and their gene products, the enzymes, determine which reactions are possible.
The metabolic pathway of glycolysis is used by almost all living beings.
An essential difference in the use of glycolysis is the recovery of NADPH as a reductant for anabolism that would otherwise have to be generated indirectly.
Glucose and oxygen supply almost all the energy for the brain, so its availability influences psychological processes.
When glucose is low, psychological processes requiring mental effort (e.g., self-control, effortful decision-making) are impaired.
In the brain, which is dependent on glucose and oxygen as the major source of energy, the glucose concentration is usually 4 to 6 mM (5 mM equals 90 mg/dL),[40] but decreases to 2 to 3 mM when fasting.
Confusion occurs below 1 mM and coma at lower levels.
The glucose in the blood is called blood sugar.
Blood sugar levels are regulated by glucose-binding nerve cells in the hypothalamus.
In addition, glucose in the brain binds to glucose receptors of the reward system in the nucleus accumbens.
The binding of glucose to the sweet receptor on the tongue induces a release of various hormones of energy metabolism, either through glucose or through other sugars, leading to an increased cellular uptake and lower blood sugar levels.
Artificial sweeteners do not lower blood sugar levels.
The blood sugar content of a healthy person in the short-time fasting state, e.g. after overnight fasting, is about 70 to 100 mg/dL of blood (4 to 5.5 mM).
In blood plasma, the measured values are about 10–15% higher.
In addition, the values in the arterial blood are higher than the concentrations in the venous blood since glucose is absorbed into the tissue during the passage of Glucose capillary bed.
Also in the capillary blood, which is often used for blood sugar determination, the values are sometimes higher than in the venous blood. The glucose content of the blood is regulated by the hormones insulin, incretin and glucagon.
Insulin lowers the glucose level, glucagon increases it.
Furthermore, the hormones adrenaline, thyroxine, glucocorticoids, somatotropin and adrenocorticotropin lead to an increase in the glucose level.
Glucose is also a hormone-independent regulation, which is referred to as glucose autoregulation.
After food intake the blood sugar concentration increases. Values over 180 mg/dL in venous whole blood are pathological and are termed hyperglycemia, values below 40 mg/dL are termed hypoglycaemia.
When needed, glucose is released into the bloodstream by glucose-6-phosphatase from glucose-6-phosphate originating from liver and kidney glycogen, thereby regulating the homeostasis of blood glucose concentration.
In ruminants, the blood glucose concentration is lower (60 mg/dL in cattle and 40 mg/dL in sheep), because the carbohydrates are converted more by their gut flora into short-chain fatty acids.
Some glucose is converted to lactic acid by astrocytes, which is then utilized as an energy source by brain cells; some glucose is used by intestinal cells and red blood cells, while the rest reaches the liver, adipose tissue and muscle cells, where it is absorbed and stored as glycogen (under the influence of insulin).
Liver cell glycogen can be converted to glucose and returned to the blood when insulin is low or absent; muscle cell glycogen is not returned to the blood because of a lack of enzymes.
Glucose fat cells, glucose is used to power reactions that synthesize some fat types and have other purposes.
Glycogen is the body's "glucose energy storage" mechanism, because it is much more "space efficient" and less reactive than glucose itself.
As a result of its importance in human health, glucose is an analyte in glucose tests that are common medical blood tests.
Eating or fasting prior to taking a blood sample has an effect on analyses for glucose in the blood; a high fasting glucose blood sugar level may be a sign of prediabetes or diabetes mellitus.
The glycemic index is an indicator of the speed of resorption and conversion to blood glucose levels from ingested carbohydrates, measured as the area under the curve of blood glucose levels after consumption in comparison to glucose (glucose is defined as 100).
Glucose clinical importance of the glycemic index is controversial, as foods with high fat contents slow the resorption of carbohydrates and lower the glycemic index, e.g. ice cream.
An alternative indicator is the insulin index, measured as the impact of carbohydrate consumption on the blood insulin levels.
The glycemic load is an indicator for the amount of glucose added to blood glucose levels after consumption, based on the glycemic index and the amount of consumed food.
Precursor
Organisms use glucose as a precursor for the synthesis of several important substances.
Starch, cellulose, and glycogen ("animal starch") are common glucose polymers (polysaccharides).
Some of these polymers (starch or glycogen) serve as energy stores, while others (cellulose and chitin, which is made from a derivative of glucose) have structural roles.
Oligosaccharides of glucose combined with other sugars serve as important energy stores.
These include lactose, the predominant sugar in milk, which is a glucose-galactose disaccharide, and sucrose, another disaccharide which is composed of glucose and fructose.
Glucose is also added onto certain proteins and lipids in a process called glycosylation.
Glucose is often critical for their functioning.
The enzymes that join glucose to other molecules usually use phosphorylated glucose to power the formation of the new bond by coupling it with the breaking of the glucose-phosphate bond.
Other than its direct use as a monomer, glucose can be broken down to synthesize a wide variety of other biomolecules.
This is important, as glucose serves both as a primary store of energy and as a source of organic carbon.
Glucose can be broken down and converted into lipids.
Glucose is also a precursor for the synthesis of other important molecules such as vitamin C (ascorbic acid).
Glucose living organisms, glucose is converted to several other chemical compounds that are the starting material for various metabolic pathways.
Among them, all other monosaccharides such as fructose (via the polyol pathway),mannose (the epimer of glucose at position 2), galactose (the epimer at position 4), fucose, various uronic acids and the amino sugars are produced from glucose.
In addition to the phosphorylation to glucose-6-phosphate, which is part of the glycolysis, glucose can be oxidized during its degradation to glucono-1,5-lactone. Glucose is used in some bacteria as a building block in the trehalose or the dextran biosynthesis and in animals as a building block of glycogen.
Glucose can also be converted from bacterial xylose isomerase to fructose.
In addition, glucose metabolites produce all nonessential amino acids, sugar alcohols such as mannitol and sorbitol, fatty acids, cholesterol and nucleic acids.
Finally, glucose is used as a building block in the glycosylation of proteins to glycoproteins, glycolipids, peptidoglycans, glycosides and other substances (catalyzed by glycosyltransferases) and can be cleaved from them by glycosidases.
Pathology
Diabetes
Diabetes is a metabolic disorder where the body is unable to regulate levels of glucose in the blood either because of a lack of insulin in the body or the failure, by cells in the body, to respond properly to insulin.
Each of these situations can be caused by persistently high elevations of blood glucose levels, through pancreatic burnout and insulin resistance.
Glucose pancreas is the organ responsible for the secretion of the hormones insulin and glucagon.
Insulin is a hormone that regulates glucose levels, allowing the body's cells to absorb and use glucose.
Without it, glucose cannot enter the cell and therefore cannot be used as fuel for the body's functions.
Glucose the pancreas is exposed to persistently high elevations of blood glucose levels, the insulin-producing cells in the pancreas could be damaged, causing a lack of insulin in the body.
Insulin resistance occurs when the pancreas tries to produce more and more insulin in response to persistently elevated blood glucose levels.
Eventually, the rest of the body becomes resistant to the insulin that the pancreas is producing, thereby requiring more insulin to achieve the same blood glucose-lowering effect, and forcing the pancreas to produce even more insulin to compete with the resistance.
This negative spiral contributes to pancreatic burnout, and the disease progression of diabetes.
To monitor the body's response to blood glucose-lowering therapy, glucose levels can be measured.
Blood glucose monitoring can be performed by multiple methods, such as the fasting glucose test which measures the level of glucose in the blood after 8 hours of fasting.
Another test is the 2-hour glucose tolerance test (GTT) – for this test, the person has a fasting glucose test done, then drinks a 75-gram glucose drink and is retested.
This test measures the ability of the person's body to process glucose.
Over time the blood glucose levels should decrease as insulin allows it to be taken up by cells and exit the blood stream.
Hypoglycemia management
Glucose, 5% solution for infusions
Individuals with diabetes or other conditions that result in low blood sugar often carry small amounts of sugar in various forms.
One sugar commonly used is glucose, often in the form of glucose tablets (glucose pressed into a tablet shape sometimes with one or more other ingredients as a binder), hard candy, or sugar packet.
Sources
Glucose tablets
Most dietary carbohydrates contain glucose, either as their only building block (as in the polysaccharides starch and glycogen), or together with another monosaccharide (as in the hetero-polysaccharides sucrose and lactose).
Unbounded glucose is one of the main ingredients of honey.
Glucose is extremely abundant and has been isolated from a variety of natural sources across the world, including male cones of the coniferous tree Wollemia nobilis in Rome, the roots of Ilex asprella plants in China, and straws from rice in California.
Commercial production
Glucose is produced industrially from starch by enzymatic hydrolysis using glucose amylase or by the use of acids.
Glucose enzymatic hydrolysis has largely displaced the acid-catalyzed hydrolysis.
Glucose result is glucose syrup (enzymatically with more than 90% glucose in the dry matter) with an annual worldwide production volume of 20 million tonnes (as of 2011).
This is the reason for the former common name "starch sugar".
The amylases most often come from Bacillus licheniformis or Bacillus subtilis (strain MN-385), which are more thermostable than the originally used enzymes.
Starting in 1982, pullulanases from Aspergillus niger were used in the production of glucose syrup to convert amylopectin to starch (amylose), thereby increasing the yield of glucose.
Glucose reaction is carried out at a pH = 4.6–5.2 and a temperature of 55–60 °C.
Corn syrup has between 20% and 95% glucose in the dry matter.
The Japanese form of the glucose syrup, Mizuame, is made from sweet potato or rice starch.
Maltodextrin contains about 20% glucose.
Many crops can be used as the source of starch.
Maize,rice,wheat,cassava,potato, barley, sweet potato,corn husk and sago are all used in various parts of the world.
In the United States, corn starch (from maize) is used almost exclusively.
Some commercial glucose occurs as a component of invert sugar, a roughly 1:1 mixture of glucose and fructose that is produced from sucrose.
In principle, cellulose could be hydrolysed to glucose, but this process is not yet commercially practical.
Conversion to fructose
Main article: isoglucose
In the USA almost exclusively corn (more precisely: corn syrup) is used as glucose source for the production of isoglucose, which is a mixture of glucose and fructose, since fructose has a higher sweetening power — with same physiological calorific value of 374 kilocalories per 100 g.
The annual world production of isoglucose is 8 million tonnes (as of 2011).
When made from corn syrup, the final product is high fructose corn syrup (HFCS).
Commercial usage
Relative sweetness of various sugars in comparison with sucrose
Glucose is mainly used for the production of fructose and in the production of glucose-containing foods.
Glucose foods, it is used as a sweetener, humectant, to increase the volume and to create a softer mouthfeel.
Various sources of glucose, such as grape juice (for wine) or malt (for beer), are used for fermentation to ethanol during the production of alcoholic beverages.
Most soft drinks in the US use HFCS-55 (with a fructose content of 55% in the dry mass), while most other HFCS-sweetened foods in the US use HFCS-42 (with a fructose content of 42% in the dry mass).
Glucose the neighboring country Mexico, on the other hand, cane sugar is used in the soft drink as a sweetener, which has a higher sweetening power.
In addition, glucose syrup is used, inter alia, in the production of confectionery such as candies, toffee and fondant.
Typical chemical reactions of glucose when heated under water-free conditions are the caramelization and, in presence of amino acids, the maillard reaction.
In addition, various organic acids can be biotechnologically produced from glucose, for example by fermentation with Clostridium thermoaceticum to produce acetic acid, with Penicillium notatum for the production of araboascorbic acid, with Rhizopus delemar for the production of fumaric acid, with Aspergillus niger for the production of gluconic acid, with Candida brumptii to produce isocitric acid, with Aspergillus terreus for the production of itaconic acid, with Pseudomonas fluorescens for the production of 2-ketogluconic acid, with Gluconobacter suboxydans for the production of 5-ketogluconic acid, with Aspergillus oryzae for the production of kojic acid, with Lactobacillus delbrueckii for the production of lactic acid, with Lactobacillus brevis for the production of malic acid, with Propionibacter shermanii for the production of propionic acid, with Pseudomonas aeruginosa for the production of pyruvic acid and with Gluconobacter suboxydans for the production of tartaric acid Potent, bioactive natural products like triptolide that inhibit mammalian transcription via inhibition of the XPB subunit of the general transcription factor TFIIH has been recently reported as a glucose conjugate for targeting hypoxic cancer cells with increased glucose transporter expression.
Recently, glucose has been gaining commercial use as a key component of "kits" containing lactic acid and insulin intended to induce hypoglycemia and hyperlactatemia to combat different cancers and infections.
Analysis
Specifically, when a glucose molecule is to be detected at a certain position in a larger molecule, nuclear magnetic resonance spectroscopy, X-ray crystallography analysis or lectin immunostaining is performed with concanavalin A reporter enzyme conjugate (that binds only glucose or mannose).
Classical qualitative detection reactions
These reactions have only historical significance:
Fehling test
Glucose Fehling test is a classic method for the detection of aldoses.
Due to mutarotation, glucose is always present to a small extent as an open-chain aldehyde.
By adding the Fehling reagents (Fehling (I) solution and Fehling (II) solution), the aldehyde group is oxidized to a carboxylic acid, while the Cu2+ tartrate complex is reduced to Cu+ and forms a brick red precipitate (Cu2O).
Tollens test
Glucose the Tollens test, after addition of ammoniacal AgNO3 to the sample solution, Ag+ is reduced by glucose to elemental silver.
Barfoed test
Glucose Barfoed's test, a solution of dissolved copper acetate, sodium acetate and acetic acid is added to the solution of the sugar to be tested and subsequently heated in a water bath for a few minutes.
Glucose and other monosaccharides rapidly produce a reddish color and reddish brown copper(I) oxide (Cu2O).
Nylander's test
As a reducing sugar, glucose reacts in the Nylander's test.
Other tests
Upon heating a dilute potassium hydroxide solution with glucose to 100 °C, a strong reddish browning and a caramel-like odor develops.
Concentrated sulfuric acid dissolves dry glucose without blackening at room temperature forming sugar sulfuric acid.
Glucose a yeast solution, alcoholic fermentation produces carbon dioxide in the ratio of 2.0454 molecules of glucose to one molecule of CO2.
Glucose forms a black mass with stannous chloride.
Glucose an ammoniacal silver solution, glucose (as well as lactose and dextrin) leads to the deposition of silver.
Glucose an ammoniacal lead acetate solution, white lead glycoside is
