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What Is The Difference Between Alpha And Beta D Glucose?

What Is The Difference Between Alpha And Beta Glucose?

What Is The Difference Between Alpha And Beta Glucose?

-glucose) is biologically active.The mirror-image of the D-glucose , -glucose, cannot be used by cells. In solutions, the open-chain form of glucose (either 'D-' or 'L-') exists in equilibrium with several cyclic isomers, each containing a ring of carbons closed by one oxygen atom. The D-glucose can exist in two forms alpha-D-glucose and beta-D-glucose. They differ only in the direction that -H and -OH groups point on carbon 1 (See the jmol images below). When alpha-glucose molecules are joined chemically to form a polymer starch is formed. When beta-glucose molecules are joined to form a polymer cellulose is formed. Glucose 3D Molecular Structures using Jsmol Note about 3D molecules -- Our files on this page now use Jsmol instead of Jmol. These files make use of Javascript which permits viewing of molecules on tablets, phones and easier use on Macs. - Jsmol is best viewed with the Chrome browser. When a glucopyranose molecule is drawn in the Haworth projection , the designation 'a-' means that the hydroxyl group attached to C-1 and the -CH2OH group at C-5 lies on opposite sides of the ring's plane (a trans arrangement), while '-' means that they are on the same side of the plane (a cis arrangement). See below. Continue reading >>

Chemical Forms Of Carbohydrates

Chemical Forms Of Carbohydrates

What is the empirical formula of most carbohydrates? What are the linear & cyclical forms of beta D-Glucose & beta D-Fructose? What are carbohydrates containing an aldehyde group called? Where is the carbonyl group? Carbohydrates containing an aldehyde group are called aldoses (at C1 and 2). An aldose has the carbonyl (C=O) group at the end of the carbon chain. What are carbohydrates containing a ketone group called? Where is the carbonyl group? those with a keto group (at C1 and 2) are called ketoses. The carbonyl group is on an internal carbon artom. Describe asymmetric centers in regards to aldoses & ketoses. Aldoses with three or more carbon atoms and ketoses with four or more carbon atoms contain asymmetric centers which are formed by carbon atoms with four different constituent atoms/groups. Is fructose non-reducing in its linear or circular form? The carbonyl at C2 in fructose will be available only in the linear form of this sugar. In circular form it is non-reducing. Is glucose a reducing sugar? Why or why not? The carbonyl at the number 1 carbon is able to donate electrons to reduce other molecules. What is the configuration of D- or L- referring to? The configuration designation of D- or L- refers to the position of the hydroxyl group on the C5 carbon atom next to the #6 C (bottom -CH2OH) or the asymmetric carbon farthest from the aldehyde or ketone group. D-sugars are written with the hydroxyl group on the right of C5 and the L-sugars with the hydroxyl group on the left. Ring form: If the last hydroxyl in the ring is down its D. If it's up its L. No. Compounds such as these which are identical in composition but differ in spatial configuration are called stereoisomers or enantiomers. The majority of sugars in the body are of the D-configuration. An anomer i Continue reading >>

Alpha- And Beta-anomeric Preference Of Glucose-induced Insulin Secretion At Physiological And Higher Glucose Concentrations, Respectively

Alpha- And Beta-anomeric Preference Of Glucose-induced Insulin Secretion At Physiological And Higher Glucose Concentrations, Respectively

Volume 180, Issue 2 , 31 October 1991, Pages 709-715 Alpha- and beta-anomeric preference of glucose-induced insulin secretion at physiological and higher glucose concentrations, respectively Author links open overlay panel IchitomoMiwa TomiyasuMurata JunOkuda Get rights and content We determined the anomeric preference of glucose phosphorylation by islet glucokinase, glucose utilization by pancreatic islets, and insulin secretion induced by glucose over a wide range of glucose concentrations. -D-Glucose was phosphorylated faster than -D-glucose by islet glucokinase at lower glucose concentrations (5 and 10 mM), whereas the opposite anomeric preference was observed at higher glucose concentrations (40 and 60 mM). At 20 mM, there was no significant difference in phosphorylation rate between the two anomers. Similar patterns of anomeric preference were observed both in islet glucose utilization and in glucose-induced insulin secretion. The present study affords strong evidence that glucokinase is responsible for the anomeric preference of glucose-stimulated insulin secretion through anomeric discrimination in islet glucose utilization. Continue reading >>

Anomeric Centre (alpha And Beta)

Anomeric Centre (alpha And Beta)

This page has been approved by the Responsible Curator as essentially complete. CAZypedia is a living document, so further improvement of this page is still possible. If you would like to suggest an addition or correction, please contact the page's Responsible Curator directly by e-mail, or using this form . The anomeric centre of a sugar is a stereocentre created from the intramolecular formation of an acetal (or ketal) of a sugar hydroxyl group and an aldehyde (or ketone) group. The two stereoisomers formed from the two possible stereochemistries at the anomeric centre are called anomers. They are diastereoisomers of one another. The configuration at the anomeric centre (that derived from the carbonyl carbon) is denoted alpha- (-) or beta- (-) by reference to the stereocentre that determines the absolute configuration. In a Fischer projection, if the substituent off the anomeric centre is on the same side as the oxygen of the configurational (D- or L-) carbon, then it is the --anomer. If it is directed in the opposite direction it is the -anomer. Example 1. Fischer projections and Haworth conformational projections of L-arabinose. Example 2. Fischer projections and Haworth conformational projections of D-fructose. In the case of D-hexopyranoses drawn in the 'usual' Haworth projection, the -D-anomer is the isomer with the anomeric substituent on the opposite face to the C5 (hydroxymethyl) substitutent, ie directed down; the -D-anomer is that with the anomeric substituent being on the same face as the C5 hydroxymethyl substitutent, ie directed up. For L-hexoses the -L-anomer has the anomeric group pointing up; the -L-anomer has this group pointing down. Example 3. Fischer projections and Haworth conformational projections of D-glucose. Continue reading >>

What's The Difference Between Alpha-glucose And Beta-glucose?

What's The Difference Between Alpha-glucose And Beta-glucose?

What's the difference between alpha-glucose and beta-glucose? beta D-glucose units makes up the structure of cellulose polysaccharides while alpha D-glucose units makes up the structure of polysaccharides starch. user9873 Nov 18 '14 at 14:12 $\alpha$-D-glucose and $\beta$-D-glucose are stereoisomers - they differ in the 3-dimensional configuration of atoms/groups at one or more positions. Note that the structures are almost identical, except that in the $\alpha$ form, the $\ce{OH}$ group on the far right is down, and, in the $\beta$ form, the $\ce{OH}$ group on the far right is up. More specifically, they are a class of stereoisomer called an anomer . Anomers are capable of interconverting in solution. All cyclic structures of monosaccharides exhibit anomeric $\alpha$ (down) and $\beta$ (up) versions. These differences occur at the anomeric acetal carbon (the only carbon with two $\ce{C-O}$ bonds. These two forms exist because all monosaccharides also have an open-chain form with one fewer stereocenter. When the chain closes to the cyclic structure, the aldehyde or ketone carbon becomes a stereocenter , and it can do so in either configuration. One configuration is preferred ($\beta$), but both exist. In the presence of acid or base (although water can fulfill this role if need be), the two anomers interconvert through the open form until dynamic equilibrium is established. The mechanism below starts with $\alpha$ in the upper left and finishes with $\beta$ in the lower right. The open-chain form is in the middle. Just to add, in the L-configuration, the situation is reversed, since you draw the CH2OH below the ring in the Haworth projection. In both cases, the structure is when the relevant groups are on the same side of the ring, and when they're on opposite sides. H Continue reading >>

Is Alpha (d+) Glucose Same As Beta (d-) Glucose?

Is Alpha (d+) Glucose Same As Beta (d-) Glucose?

Is alpha (D+) glucose same as beta (D-) glucose? No. In the name D(+) Glucose, D represents the orientation of the hydroxyl group at the chiral carbon that is farthest from the highest oxidised carbon (Aldehyde group in this case) with respect to glyceraldehyde. D says that the hydroxyl group is on the right side (In fischer projection). L says the opposite. Where as (+) and (-) represent the direction of rotation of plane polarised light {Optical rotation} (Determined experimentally) by the solution as a whole. When a water molecule adds to the glucose molecule, the aldehyde group turns into hemiacetal (Ring is formed between 1st and 5th carbon), making the first carbon (previously aldehyde) chiral. Alpha and Beta represent the orientation of hydroxide group (R and S) at that new chiral carbon (Anomeric carbon). Hence those forms are called anomers. Pure Alpha glucose has a positive optical rotation and the Beta form has the opposite rotation (but of different magnitude). The compounds which you have mentioned in the question are pure alpha and pure beta forms of glucose. If you get some random D glucose from somewhere and you some how determined that it has a positive optical rotation,it doesnt mean that it is alpha D glucose. It may also contain beta D glucose each cancelling the effect of other and ultimately resulting a positive optical rotation (Overall dominated by alpha D glucose). Continue reading >>

Differences Between Alpha And Beta Glucose

Differences Between Alpha And Beta Glucose

Home / Science & Nature / Science / Chemistry / Differences Between Alpha and Beta Glucose Differences Between Alpha and Beta Glucose Glucose is the unit of carbohydrate and show the unique characteristic of the carbohydrate. Glucose is a monosaccharide and reducing sugar which is the main product of photosynthesis in plants. Chlorophylls produce glucose and oxygen using inorganic carbon and water. So, sunlight is fixed into chemical energy through glucose. Then glucose is further converted into starch and stored in plants. In respiration, glucose is broken down to ATP and provides energy to the living organisms resulting carbon dioxide and water as the final product of respiration. Glucose can be found in animals and humans, in their blood stream. Glucose is six carbon molecule or called hexose. The formula of the glucose is C6H12O6, and this formula is common to other hexoses too.Glucose can be in cyclic chair form and in chain form. Since glucose has aldehyde, ketone and alcohol functional groups it can be easily converted into straight chain form to cyclic chain form. The tetrahedral geometry of the carbons makes six membered stable ring. Hydroxyl group on the carbon five in the straight chain is linked with carbon one making hemiacetal bond (Mcmurry, 2007). So the carbon one is called anomeric carbon. When glucose is figured into fischer projection, this the hydroxyl group of the asymmetric carbon is drawn in the right and called D- glucose. If the hydroxyl group of the asymmetric carbon is in the left side in the fischer projection, it is L- glucose. D- glucose has two sterioisomers called alpha and beta differing from specific rotation. In a mixture, these two forms can be converting into each other and forms equilibrium. This process is called mutarotation. The Continue reading >>

Initial Steps Of Alpha- And Beta-d-glucose Binding To Intact Red Cell Membrane.

Initial Steps Of Alpha- And Beta-d-glucose Binding To Intact Red Cell Membrane.

Initial steps of alpha- and beta-D-glucose binding to intact red cell membrane. (1)Biophysical Laboratory, Harvard Medical School, Boston, Massachusetts 02115. The kinetics of the initial phases of D-glucose binding to the glucose transport protein (GLUT1) of the human red cell can be followed by stopped-flowmeasurements of the time course of tryptophan (trp) fluorescence enhancement. Anumber of control experiments have shown that the trp fluorescence kinetics arethe result of conformational changes in GLUT1. One shows that nontransportableL-glucose has no kinetic response, in contrast to D-glucose kinetics. Othercontrols show that D-glucose binding is inhibited by cytochalasin B and byextracellular D-maltose. A typical time course for a transportable sugar, such asD-glucose, consists of a zero-time displacement, too fast for us to measure,followed by three rapid reactions whose exponential time courses have rateconstants of 0.5-100 sec-1 at 20 degrees C. It is suggested that the zero-timedisplacement represents the initial bimolecular ligand/GLUT1 association.Exponential 1 appears to be located at, or near, the external membrane face whereit is involved in discriminating among the sugars. Exponential 3 is apparentlycontrolled by events at the cytosolic face. Trp kinetics distinguish the Kd ofthe epimer, D-galactose, from the Kd for D-glucose, with results in agreementwith determinations by other methods. Trp kinetics distinguish between thebinding of the alpha- and beta-D-glucose anomers. The exponential 1 activationenergy of the beta-anomer, 13.6 +/- 1.4 kcal mol-1, is less than that ofalpha-D-glucose, 18.4 +/- 0.8 kcal mol-1, and the two Arrhenius lines cross atapproximately 23.5 degrees C. The temperature dependence of the kinetic response following alpha-D-glucose Continue reading >>

Differences Between Alpha And Beta Glucose

Differences Between Alpha And Beta Glucose

Differences Between Alpha and Beta Glucose Categorized under Chemistry | Differences Between Alpha and Beta Glucose Encountering the term glucose makes us think of something sweet, which is, of course, true. If you remember what you studied during your biology or chemistry class, glucose is a form of carbohydrate; and carbohydrates give us the energy we need throughout the day. For us humans, glucose is considered the most important, simple sugar because it is a very essential factor in our metabolism. Though glucose is called a simple sugar, its chemistry is really complex. Glucose, which is oftentimes referred to as dextrose, is made up of 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. When combined, it can take the form of a variety of arrangements; thus isomers are born. Among the first two isomers that chemists discovered were the alpha glucose and the beta glucose. Both fall under the category of glucose, but what are the differences between these two? If we are to compare their chemical structures, alpha glucose and beta glucose only differ in the way each carbon, hydrogen, and oxygen atoms are attached to one another. Though they have the same chemical composition, the way their atoms combine gives you two different structures. If we are to describe the molecules present in the alpha glucose, they are compressed but can be easily taken apart. On the other hand, the beta glucose molecules are solidly packed; hence, they cannot be easily taken apart. In other words, the molecules of beta glucose are very stable. Chains of alpha glucose compose starch. Since the foundation of starch is alpha glucose, it can be easily broken down into simple sugars. Meanwhile, chains of beta glucose compose cellulose. Unlike starch, cellulose is not easy to break down; henc Continue reading >>

Difference Between Alpha And Beta Glucose

Difference Between Alpha And Beta Glucose

Home Science Chemistry Biochemistry Difference Between Alpha and Beta Glucose Difference Between Alpha and Beta Glucose Glucose is a simple carbohydrate . It is a sugar that has a sweet taste. The molecular formula of glucose is C6H12O6. The structure of glucose can be given in different ways such as the Fischer projection, Haworth projection or Chair conformation. The most accurate way of the representing glucose is the chair confirmation, which is typically the most stable structure of most of the cyclic molecules. The major isomers of glucose include D-glucose and L-glucose. According to the chair confirmation, there are two isomers of D-glucose that can be found in nature. Those are alpha glucose and beta glucose. The main difference between alpha and beta glucose is that the OH group attached to the first carbon atom in alpha glucose is located on the same side as the CH2OH group whereas the OH group attached to the first carbon atom of in beta glucose is located on the opposite side from the CH2OH group. Key Terms: -Glycopyranose, -Glycopyranose, Alpha Glucose, Beta Glucose, Chair Confirmation, Glucopyranose, Glucose, Oxygen Bridge Alpha Glucose is an isomer of D-glucose whose OH group of the first carbon atom is located on the same side as the CH2OH group. Alpha glucose is a sugar. When considering the chair confirmation structure, alpha glucose is a cyclic structure having four OH groups attached to the main carbon chain. The cycle is formed through an Oxygen bridge. That means, two carbon atoms of the terminal of the main carbon chain are attached through an oxygen atom. The ring structure is not planar and is a 3D structure. In order to avoid any confusion, the chair confirmation of glucose is called glucopyranose. Therefore, alpha glucose is also known as -g Continue reading >>

Ch25: Alpha And Beta Forms

Ch25: Alpha And Beta Forms

The cyclic forms of carbohydrates can exist in two forms, -and - based on the position of the substituentat the anomeric center. The two forms are sometimes described as "anomers" since they areisomersatthe anomeric center. To assign the cyclic form of a carbohydrate as the -or - form look at the relative positions ofthe -CH2OH group and -OH (or -OR) group at the anomeric center. In the - form, the exocyclic Ogroup at the anomeric center is on the opposite face to the-CH2OH group, and In the - form, the exocyclic Ogroup at the anomeric center is on the same face as the -CH2OHgroup. If a mixture of the - and -anomers are present, then this is often represented by using a "wavy" lineto represent the bond: In general the two forms are stable solids, but in solution they rapidlyequilibrate (see mutarotation). The following figures shows several representations of the - and - anomers of D-glucose. You should Manipulate the 3D JMOL images until you can confirm the important relationship. Dr. Ian Hunt , Department of Chemistry, University of Calgary Continue reading >>

Molecular Recognition Of Carbohydrates

Molecular Recognition Of Carbohydrates

Carbohydrates are poly hydroxy compounds which form a ring structure in water. The smallest building block is called a monosaccharide of which polysacharides consist of. Example: D-glucose is shown in its linear (center), as a pyranose (>99% in water), and as a pentose. In this cyclyzation process an alpha (top right) and a beta anomer (bottom right) are formed which are shown in a ball and stick model (oxygen atom in red) Example: Two disaccharides which consist of D-glucose units are shown. In maltose the glucose units are connected with anomeric center (1) in alpha configuration to the second unit at the 4 position. Cellobiose differs from maltose only in the configuration of the linking anomeric center. Consequently the corresponding polymers do have a different biological function. Starch which is the polymer of maltose can be digested by humans whereas cellulose cannot. Carbohydrate-carbohydrate interactions are the initial step in cell recognition and in many other important biological processes.Understanding these molecular interactions at atomic level will be valuable in the design of specific receptors for carbohydrates.X-ray structures of glycoproteins do not often show a resolved carbohydrate part which make modeling studies even more important. Development of the computational framework: Optimizing parameters of the potential energy functions . Pure liquid simulations: The parameters describing the inter-molecular interactions (q, A, C) are optimized to reproduce some physical properties such as the heat of vaporization and the density of a pure liquid. Rotational profiles: The parameters describing the intra-molecular interactions (V, q, A,C) are optimized to reproduce energetics of the conformations in the gas phase. Simple carbohydrates such as monosacc Continue reading >>

Alpha And Beta Glucose Molecules - Dual View For Comparison Purposes

Alpha And Beta Glucose Molecules - Dual View For Comparison Purposes

Alpha and Beta Glucose molecules - dual view for comparison purposes Alpha and beta glucose differ only in the direction that -H and -OH groups point on carbon 1 (labelled). The description below assumes that the ring is orientated so that the movement from carbon atom C1 to C6 is in a clockwise direction. Alpha glucose has an -OH [hydroxyl] group (red sphere attached to white sphere) that points "downwards", away from the ring, whereas the -OH on carbon 1 of beta glucose is above the ring. This may be seen if the molecules are seen from the edge . Click here to move back . These two forms of glucose are (stereo)isomers, because they contain the same atoms, but they differ in the arrangement of their atoms in space. They can also be called epimers because they represent different configurations of atoms about a single stereogenic centre - in this case carbon 1. They can also be called anomers because they differ only in configuration at the hemiacetal carbon 1, also called the anomeric carbon. This difference is not enough to warrant giving these two forms different names, apart from -D-glucopyranose and -D-glucopyranose of course! This orientation is the reason for the difference between the disaccharides maltose and cellobiose .In maltose there is a (1-4) glycosidic bond formed between one -glucose and another; in cellobiose a (1-4) glycosidic bond is formed between one -glucose and another, and this has important consequences for the types of molecules which can be formed as a result of further condensation reactions. Alpha, 1-4 linkages make starch (amylose and amylopectin) fairly easily broken down by enzymes whereas beta, 1-4 linkages result in linear microfibrils of cellulose which are difficult to break down. Continue reading >>

What Is The Difference Between An Alpha Anomer And A

What Is The Difference Between An Alpha Anomer And A

What is the difference between an alpha anomer and a beta anomer an alpha What is the difference between an alpha anomer and a This preview shows page 21 - 22 out of 26 pages. What is the difference between an alpha anomer and abeta anomer?an alpha anomer holds the alcohol group on off ring carbon 6 trans to carbon one's alcohol group, for thebeta anomer the alcohol group on off ring carbon 6 is cis to carbon one's alcohol group. A beta glucose is amore stable molecule as more bulky substituents are equatorial, and it also has a higher melting point.What is the difference between a pyranose and afuranose?A pyranose is a monosaccharide six member ring whereas a furanose is a five membered monosaccharidering.What is mutarotation?The change in specific rotation toward an equilibrium valueWhat is schiff' reagent and what does it test for?D plus glucose does not react with schiff's reagent because it requires a high concentration of free aldehyderather than hemiacetals in order to give a positive test. Although glucose will exist in 3 differentmutarotational states being alpha d plus, beta D plus and an open chain form of d plus glucose which has analdehyde but is immeasureable due to a heavy preference towards the cyclical forms especially the morestable beta product.What is the anomeric effect?Sometimes equilibrium will favor an alpha anomer vs a beta anomer. This is odd because an alpha anomershould be less stable due to the presence of axial substituents on the ring, however due to hyperconjugationthe axially orientated orbitals an electronegative substituent will be pulled into an axial orientation.What is a glycoside and how can we make one?A carbohydrate acetal is generally called a glycoside. Add an alcohol and Hydrogen chloride, and analiphatic alcohol molecule to Continue reading >>

D And L Sugars, Alpha And Beta Anomers

D And L Sugars, Alpha And Beta Anomers

SDN members see fewer ads and full resolution images. Join our non-profit community! I've probably asked four different people this same question, but it seems nobody really knows for sure. My question is this: Is there a correlation between a D or L sugar and Alpha or Beta anomers? In other words, are D sugars always Beta anomers (and vice versa)? I've probably asked four different people this same question, but it seems nobody really knows for sure. My question is this: Is there a correlation between a D or L sugar and Alpha or Beta anomers? In other words, are D sugars always Beta anomers (and vice versa)? I'm not 100% sure on this but I'm inclined to say the two aren't related. Since D and L mainly refer to the stereochemistry of the highest numbered stereocenter and anomers arise from nucleophilic attack of the carbonyl carbon, I would assume that D/L designation doesn't really affect what anomer is formed. Not quite. Just wanted to clear up--you D and L stereoisomers is still "retained" in the ring form. In the Haworth projections, This is an alpha, L sugar. It's L because the methoxy group is pointing down. It's alpha because the anomeric carbon has the OH group pointing in the opposite direction. I'm not sure I understand what you mean. How could you tell the methoxy group is pointing down? From my understanding the sugar is being tilted in Haworth's Projection so that the wedges are pointing towards you. Continue reading >>

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