Difference Between Alpha and Beta Glucose

Main Difference – Alpha vs 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 Areas Covered

1. What is Alpha Glucose
      – Definition, Structure, Properties
2. What is Beta Glucose
      – Definition, Structure, Properties
3. Similarities Between Alpha and Beta Glucose
      – Outline of Common Features
4. What is the Difference Between Alpha and Beta Glucose
      – Comparison of Key Differences

Key Terms:  α-Glycopyranose, β-Glycopyranose, Alpha Glucose, Beta Glucose, Chair Confirmation, Glucopyranose, Glucose, Oxygen BridgeDifference Between Alpha and Beta Glucose - Comparison Summary

What is Alpha Glucose

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. 

Difference Between Alpha and Beta Glucose

Figure 1: Alpha D-Glucose

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 α-glycopyranose. The melting point of alpha glucose is about 1460c.

Alpha glucose can easily be crystallized from its aqueous solution.  The solid crystals appear as white crystals. The chair confirmation of alpha glucose shows four chiral carbon atoms. (C2, C3, C4 and C5). Therefore, alpha glucose is highly optical active. Alpha glucose act as the building block of starch.

What is Beta Glucose

Beta glucose is an isomer of D-glucose whose –OH group of the first carbon atom is located on the opposite side from the –CH2OH group.  Beta Glucose is also a sugar. It has four –OH groups attached to the main carbon chain. Beta glucose is also called β-glycopyranose. It is a cyclic structure and has four chiral carbon atoms, same as in alpha glucose. Therefore, beta glucose is also optically active.

Main Difference - Alpha vs Beta Glucose

Figure 2: Beta D-Glucose

The melting point of beta glucose is about 1500C. It can be crystallized from its aqueous solution as white crystals of β-glycopyranose or β-glycopyranose hydrate form. The polymerization of beta glucose results in cellulose.

Similarities Between Alpha and Beta Glucose

  • Alpha and beta glucose are simple sugars.
  • Both have four –OH groups in their chemical structure.
  • The spatial arrangement of –OH groups (except for the –OH group at first carbon) is the same.
  • Both can be crystallized from their aqueous solutions.
  • Both sugars are optically active due to the presence of chiral carbons.

Difference Between Alpha and Beta Glucose

Definition

Alpha Glucose: Alpha glucose is an isomer of D-glucose that has the –OH group of the first carbon atom positioned on the same side as the –CH2OH group.

Beta Glucose: Beta Glucose is an isomer of D-Glucose that has the –OH group of the first carbon atom positioned on the opposite side from the –CH2OH group. 

Melting Point

Alpha Glucose: The melting point of alpha glucose is 1460C.

Beta Glucose: The melting point of beta glucose is 1500C.

Crystallization

Alpha Glucose: Alpha Glucose can be crystallized as α-glycopyranose from its aqueous solution.

Beta Glucose: Beta Glucose can be crystallized as either β-glycopyranose or as β-glycopyranose hydrate from its aqueous solution.

Conclusion

D-glucose is the most stable and abundant isomer among various isomers of glucose. When considering the chair confirmation of D-glucose, there are two different forms of d-glucose as alpha glucose and beta glucose. The main difference between alpha and beta glucose is the position of the -OH group attached to their first carbon atom.

References:

1.Wasserman, Robin. “What Is Alpha Glucose?” LIVESTRONG.COM. Leaf Group, 17 Nov. 2015. Web. 07 July 2017. 
2.Hunt, Dr Ian R. “What do the α- and β- forms look like?” Ch25: alpha and beta forms. N.p., n.d. Web. . 07 July 2017. 

Image Courtesy:

1.”Alpha-D-Glucose” By Yikrazuul – Own work (Public Domain) via
2. “Beta-D-Glucose” By Yikrazuul – Own work (Public Domain) via

About the Author: Madhusha

Madhusha is a BSc (Hons) graduate in the field of Biological Sciences and is currently pursuing for her Masters in Industrial and Environmental Chemistry. Her interest areas for writing and research include Biochemistry and Environmental Chemistry.

Leave a Comment


Related pages


difference between meiosis i and meiosis iiis baking soda and bicarbonate of soda the same thingdefine photoautotrophsdifference between privacy and confidentialitydifference between syllabus and curriculumdefinition tensile strengthcompare and contrast transcription and translationsashimi sushi differencedefine multinationalsthe difference between lemon and limewhat is the difference between a fold and a faultdifference between supplier and vendornova supernovaexamples of organelles in the human bodywhat is satire definitionpolyp and medusa formsvolatile substance definitionwhat is non inverting amplifierinverted commas quotation markscommon law and civil law similaritieswhat are some examples of indefinite pronounsallyl carbocationbinary fission yeastcentripital force equationdifference between bmr and rmrmild steel vs stainless steel strengthcrossing over definition geneticsmoral of the little red riding hoodvitamin b complex vs b12meaning of dusk to dawnneurotic mental illnesssn1 sn2 reactionsovertone physics definitionant and the grasshopper story with moralwhat is the difference between duke and princeaverage accounting return calculatordifference between emf and terminal potential differencedefinition pluripotentagarose chemical formulahelping verb linking verbglobal company vs multinational companydefinition dialectcpap vs bipap differencewhat is the difference between an invention and an innovationexplain the gold foil experimentfacetious definitionpnp and npn differencepost modernism vs modernismexample of polar moleculesresting metabolic rate vs basal metabolic ratedefine cation and anionethanoic acid ethanoltone and mood of a poempositive acceleration meaningcrude oil vs petroleumdifference between vitiligo and leucodermaallylic carbocationlead sulphate solubilitycilia flagellawhat is the difference between capital and capitolcircumlocution sentencen p type semiconductorsn1 reactivity ordercold and warm blooded animalscalculating cpi formulamanic depressive disorder vs bipolarfreezing point definition chemistrybicarbonate of soda vs baking sodadifference between prose and poetrydefinition of isotonic solutionpure substance chemistrydifference between sherbet and ice creamadverbs of negationdifference between narcolepsy and cataplexytypes of meristematic tissue in plantswhat is the difference between plant mitosis and animal mitosisdefinition of conductor and insulatorisopropyl chemical formulavolatile and nonvolatile solute