7 Difference between Alpha and Beta Glucose (With Table)

Glucose is a simple form of carbohydrates. Most food consumed by animals is stored in the body in form of glucose to be used later.

In plants, glucose is produced when photosynthesis takes place. The plants utilize the light energy from the sun to form their own food which is glucose.

The atoms or molecules in the glucose structure are arranged in different ways according to Fischer’s projection. The major ways are the chair conformation and Haworth projection.

The isomers; alpha and beta are the major ones formed from chair conformation. They are simple sugars having the same molecular formulae.

So, what is the main difference between alpha and beta glucose? Alpha glucose has the –OH group attached to the first carbon atom on the same side, -CH2OH, while beta glucose has the –OH group attached to the first carbon atom on the opposite side.

For more information about the difference between alpha and beta glucose in tabular form continue reading the article. You will also get to learn of the similarities between the two.

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Comparison Table (Alpha vs Beta Glucose)

Basic TermsAlpha GlucoseBeta Glucose
MeaningIt is an isomer of D-glucose that has the –OH group attached to the first carbon atom positioned on the same side.It is an isomer of D-glucose that has the –OH group attached to the first carbon atom on the opposite side.
Melting pointIt melts at 146degrees Celsius.It melts at 150 degrees Celsius.
CrystallizationIt can be crystallized as a-glycopyranose from its aqueous solution.It can be crystallized as either B-glycopyranose or B-glycopyranose hydrate from its aqueous solution.
StabilityIt is comparatively less stable as the molecules are compact.It is more stable.
BondingThe bond between two alpha molecules results in the formation of disaccharides.The bond between two beta molecules results in the formation of cellobiose.
ConversionIt can be easily converted to beta glucose.It can easily be converted into alpha glucose.
Enzyme functionStarch is a polymer of alpha glucose that can be broken easily by enzymes.Cellulose is a polymer of beta glucose that cannot be broken easily by enzymes.

What is Alpha?

Alpha glucose is an isomer of D-glucose in which the –OH group is attached to the first carbon atom on the same side of the CH2OH group.

It has a cyclic structure with four –OH groups attached to the carbon chain. The two carbon atoms at the terminals of the carbon chain are joined through an oxygen bond.

It forms a three-dimensional structure and is known as glycopyranose. It is less stable as it has compact molecules. This makes it easy to be converted to beta glucose.

The bond of two alpha glucose molecules results in the formation of disaccharides called maltase. The polymer of alpha glucose is starch which can easily be broken down by enzymes.

What is Beta?

Beta glucose is an isomer of D-glucose in which the –OH group is attached to the first carbon atom on the opposite side of the CH2OH group.

It has a cyclic structure which is the same as alpha glucose. It has the –OH group attached to the main carbon chain.

It is more stable as compared to alpha glucose. It has a higher melting point and has a specific rotation of 18.7 degrees. It can also be easily converted to alpha glucose.

Glycosidic bond of two beta glucose molecules results in the formation of cellobiose. The polymer is known as cellulose which cannot easily be broken by enzymes.

Main Difference between Alpha and Beta

  1. Alpha glucose has the –OH group attached to the first carbon atom on the same side of the CH2OH group while beta glucose has the –OH group attached to the first carbon atom on the opposite side of the CH2OH group.
  2. Alpha glucose is comparatively less stable while beta glucose is more stable.
  3. Alpha glucose has a lower melting point while beta glucose has a comparatively higher melting point.
  4. Alpha glucose can easily be broken down by enzymes while beta glucose cannot be easily broken down by enzymes.
  5. The bond between two alpha glucose molecules results in disaccharides while the bond between two beta glucose molecules results in celloboise.

Similarities between Alpha and Beta

  1. Both are simple sugars.
  2. Both have four –OH groups in their chemical structure.
  3. Both are optically active due to the presence of chiral carbon.
  4. Both can be crystallized.
  5. Both have a same spatial arrangement of –OH group.

Conclusion

Among various isomers of glucose, D-glucose is the most stable and abundant. The two different forms of D-glucose that result from chair confirmation are alpha and beta glucose.

However, the two are different. The main difference between alpha and beta glucose molecules is the position of the –OH group whereby in alpha it is attached to the first carbon on the same side while in beta glucose it is attached to the first carbon on the opposite side.

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