Threonine is the uncharged polar amino acid. It is an essential amino acid as it is not manufactured in our body. It must be provided through food to our body. It has two chiral centers. It has four steroisomers. Threonine is the hydrophilic molecules and has a hydroxyl group. It is glucogenic as well as ketogenic.
It is present protein rich foods. Some of its sources are as follow.
Animal Sources: Threonine is present in high amount in meat, eggs, dairy products, cottage cheese, and fish.
Plant sources: Threonine is also present in many leafy vegetables, lentils, wheat, beans, mushrooms, grains, sesame seeds and nuts.
In the body it is found in large amount in the skeletal muscles, heart and central nervous system.
Threonine is not synthesized in our body but it is formed in many plants and microorganism with the help of various enzymes from the other amino acid asparate. These are aspartokinase, homoserine dehydrogenase, thronine synthase, homoserine kinase, and asparatate semialdehyde dehydrogenase.
Threonine gives rise to pyruvic acid which can forms either the glucose or acetyl CoA. The latter may either enter the citric acid cycle or may form the acetoacetyl CoA which is a precursor of ketone bodies.
Thronine also form glycine which itself is an important amino acid as it acts as inhibitory neurotransmitter.
Threonine also gives rise to propionly-CoA which can then form succinyl CoA, an important component of the citric acid cycle.
It has also important role in maintaining the normal functioning of our various system like central nervous system, cardiovascular system, liver and immune system.
It helps in the synthesis of collagen and elastin present in the skin. It maintains the normal protein balance in the body. It makes our muscle strong and powerful. It also plays role in making our teeth strong and also promotes early heeling of wounds.
Threonine has also found to aid antibodies production which are major components of our immune system. These antibodies combat with various infections, microbes and foreign bodies.
Threonine also prevents fat accumulation in the liver as it enhances fats and fatty acid digestion thus helping lipotropic function of the liver.
Threonine supplements have seemed to be useful in treating various diseases due to lesion on central nervous system like amyotrophic lateral sclerosis disease as threonine produces glycine. Multiple scleroses symptoms have also been alleviated by the use of this amino acid. The dose of threonine may not be taken in excess amount as it may damages the liver and kidney functions.