Amino acids are organic compounds, which contain at least one amino group (-NH2) and a carboxy (-COOH) group and an organic R group that gives a distinct property to each amino acid. The expanded form of amino acid is alpha-amino carboxylic acid. Each amino acid contains a central carbon atom called α-carbon, with an amino and a carboxyl group. The formula of an amino acid is. There are many types of amino acids with their distinct properties; let’s explore them in detail.
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Physical and Chemical Properties of Amino Acids
To know further about the types of amino acids, first, let’s read about the various physical and chemical properties of amino acids.
Physical Properties
- The amino acids have a high melting point, which is usually greater than 200 degrees
- Amino acids are soluble in water and slightly soluble in alcohol. But, in methanol, ethanol, and the propanol. The chief factor responsible for the solubility in amino acids is the R-group and the pH of the solvent.
- The amino acid can decompose on getting exposed to high temperatures.
- Amino acids are colorless and crystalline solid.
- The amino acids have the skill to connect with a peptide bond involving their amino and carboxylate groups.
Chemical Properties
- Zwitterionic property
These are molecules with functional groups. Amino acids are best-known zwitterions. In the amino group, the -NH2 group picks up H+ from the -COOH group and, in turn, leaves a zwitterion.
- Amphoteric property
Amino acids are amphoteric, which means they act as both acids as well as a base.
- Ninhydrin test
In this test, 1 ml of Ninhydrin solution and 1 ml of protein solution get heated together and, in turn, form a violet color indicating the presence of a type of amino acid.
Other crucial chemical properties include the Xanthoproteic test, reaction with Sanger’s reagent, reaction with nitrous acid, etc.
Types of Amino Acids
Now that the term amino acid is clear enough, here are the different main types of amino acids that you must know.
- Isoleucine
Type of amino acid used in the biosynthesis of protein
Formula: C6H13NO2
- Leucine
Used in the liver, fat tissue, and muscle tissue
Formula: C6H13NO2
- Lysine
Lysines are the building blocks of protein. It is also used in medicines to prevent and treat cold sores.
Formula: C6H14N2O2
- Methionine
Methionine is also building blocks of protein. These are found in meat and dairy products.
Formula: C5H11NO2S
- Phenylalanine
Phenylalanine is present in the breast milk of mammals.
Formula: C9H11NO2
- Threonine
Type of amino acid used in the biosynthesis of proteins.
Formula: C4H9NO3
- Tryptophan
Tryptophan is amino acids used for nitrogen balance in adults and growth in infants.
Formula: C11H12N2O2
- Valine
Used in the interior of globular proteins helping to determine the three-dimensional structure
Formula: C5H11NO2