Alanine

Alanine

Alanine molecule in motion

Structural formula of L-Alanine

Alanine is an alpha-amino acid that is used in the biosynthesis of proteins. It contains an amino group, a carboxylic acid group, and a side chain methyl group, making it a non-polar, aliphatic amino acid. Alanine is classified as a non-essential amino acid, meaning it can be synthesized by the human body and does not need to be obtained directly through the diet.

Structure

Alanine has the chemical formula C₃H₇NO₂. The IUPAC name for alanine is 2-aminopropanoic acid. The molecular structure of alanine consists of a central carbon atom (the alpha carbon) bonded to an amino group (NH₂), a carboxyl group (COOH), a hydrogen atom, and a methyl group (CH₃), which is the side chain.

Stereochemistry

Alanine exists in two enantiomers, L-alanine and D-alanine, which are mirror images of each other. In biological systems, L-alanine is the form that is incorporated into proteins. The chirality of alanine is important for its function in protein structure and enzyme activity.

Biosynthesis

Alanine can be synthesized in the body through the transamination of pyruvate, a key intermediate in glycolysis. This reaction involves the transfer of an amino group from an amino acid, such as glutamate, to pyruvate, forming alanine and alpha-ketoglutarate.

Function

Alanine plays a crucial role in glucose-alanine cycle, which helps in the transport of nitrogen from muscle tissue to the liver. In this cycle, alanine is formed in muscle cells by the transamination of pyruvate. It is then transported to the liver, where it is converted back to pyruvate, which can be used for gluconeogenesis to produce glucose.

Metabolism

In the liver, alanine can be converted into pyruvate by the enzyme alanine transaminase. This pyruvate can then enter the citric acid cycle or be used for gluconeogenesis. Alanine is also involved in the synthesis of other amino acids and metabolic pathways.

Zwitterion Form

In aqueous solution, alanine exists predominantly as a zwitterion, a molecule with both positive and negative charges. The amino group is protonated (NH₃⁺), and the carboxyl group is deprotonated (COO^-), resulting in a neutral overall charge.

Gallery

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  Synthesis of alanine - step 1

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  Synthesis of alanine - step 2

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  Zwitterionic form of alanine

Related pages

• Amino acid
• Protein
• Transamination
• Gluconeogenesis

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  Alanine

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  L-Alanine structure

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  Alanine

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  Synthesis of alanine - step 1

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  Synthesis of alanine - step 2

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  Zwitterion form of alanine