DL-Threonine hydrate(2:1)

Physical and chemical properties

It appears as white orthorhombic crystal or crystalline powder, being odorless with slightly sweet taste. It has a melting point of 255~257 ℃ (decomposition), [α] 25D =-18.5 (concentration = 2, water) and a specific rotation of-28.3 (c = 1.1, water). It is insoluble in ethanol, ether and chloroform but easily soluble in water (25 ℃, 20,80 ℃ when 55). It is easily subject to decomposition when coming across alkali. L-Threonine is essential amino acids of human body with the physiological effect being 2 times of the DL-body. It is used as a food fortifier, but also for medicine. Lack of it in the human body will cause loss of appetite and fatty liver.

Figure 1 is the molecular structure of threonine.

Essential amino acids

L-threonine is the amino acid composition of protein, isolated from oat protein in 1925, having L-body and DL-body with non-ionized polar hydroxyl side chain, exhibiting hydrophilic and is nutritionally essential amino acids.
Amino acids can coordinate the vitamins and minerals to maintain the normal function of the body. For example: tyrosine deficiency can lead to iron deficiency anemia; methionine and/or taurine deficiency or metabolic disorders, and the occurrence of allergic diseases and autoimmune diseases; the elderly, if lack of tyrosine, phenylalanine, histidine and tryptophan, can lead to depression or neurological diseases; leucine, isoleucine and valine can supply muscle energy, and therefore can treat trauma and infected patients.
Actions of applying amino acids as dietary supplements, health food or the drugs of hepatitis, nephritis patients has begun in foreign countries. But has not been vigorously carried out in the country. Amino acids generally have L (L) and D (D), two forms, only the L-form will be decomposed by body's enzyme to be utilized. Generally it is taken of the free amino acids, namely the white crystals of amino acids and installed in the capsule to take so that it is easy to be absorbed and penetrate into the blood. Each amino acid has a special effect on the body. The intake of amino acids is preferably to be taken between breakfast and lunch while taking vitamin B6 and vitamin C to help the absorption of amino acids. If you take a complex amino acid, including all the essential amino acids, you must be separated by one and a half hours after each meal. It is best not to take a single amino acid, the amino acids you need can be mixed in other amino acids to form a composite amino acid, giving a better efficacy.
Threonine can help the body maintain protein balance. It can play a role in the formation of collagen and elastin. When threonine and aspartic acid and methionine are used in conjunction, it has anti-fatty liver effect. Threonine exists in the heart, the central nervous system and skeletal muscle, being able to prevent the accumulation of fat in the liver. It can promote the production of antibodies to enhance the immune system.
In food, cereal has a low threonine content, so vegetarians are prone to obtain threonine deficiency.
Animal feed and cake feed are rich in threonine. Threonine can promote animal growth and nitrogen balance, chicken threonine deficiency, loss of appetite, a sharp decline in body weight and low feed utilization efficiency. The commercial additives of threonine contains two types, L-and DL-type. Animals can not use D-threonine while the DL threonine valence is 50% of the L-threonine. The appearance is white to light brown.

Threonine metabolism

The threonine catabolism is analogous to serine, and the amino group is removed via a common dehydratase to give α-ketobutyric acid. The α-ketobutyric acid metabolism is similar as pyruvic acid (α-ketopropionic acid), can undergo oxidation decarboxylation to produce propionyl CoA, followed by reduction for generation of alpha hydroxybutyric acid and the transamination to give α-aminobutyric acid.
Alpha hydroxybutyric acid and alpha-aminobutyric acid appear in the urine while propionyl CoA can be converted into succinyl CoA to get into the tricarboxylic acid cycle, and further get into the gluconeogenesis pathway through oxaloacetate.
Hydroxybutyric acid can also be decomposed by the threonine aldolase in liver and renal into glycine and acetaldehyde. Aldehyde can be oxidized by dehydrogenase into acetic acid. Glycine and acetic acid, respectively, get into the glycine metabolic pool (see "glycine and its metabolism") and acetic acid metabolic pool, which is mainly converted into acetyl CoA, and further be used.
In recent years, threonine has been found in the liver by dehydrogenation and decarboxylation to produce ammonia acetone, α-ammonia-β-ketobutyric acid may be intermediate, but for aminopropanaminic catabolic pathway, or by α-ketopropanol or by methylglyoxal and lactic acid to pyruvate.

Preparation

1. Fermentation: take sugar, ammonia homoserine as raw material, applying
producing Micrococcus glutamicus or Brevibacterium for fermentation, and then separate to get L-body and DL-body.
2. Casein, silk protein and sericin are subject to hydrolysis, and then ion
 exchange resin purification to obtain the L-threonine.
3. glycine copper and acetaldehyde are taken as raw materials for reaction in
the alkaline medium to generate DL-body. L-seed is inoculated in DL-in vivo, and the L-form is obtained by resolving the anti-L-form.
4. take crotonic acid as raw material for reaction with ethoxy mercury,
potassium bromide and methanol, and further subject to demercuration, followed by ammoniation by ammonia, followed by acidification under the action of formic acid and acetic anhydride, and finally hydrolysis in hydrobromic acid to obtain the DL-body.
⑤ acetaldehyde is reacted with amino nitrile to obtain the DL-body.
⑥ take ethyl acetoacetate as raw material for reaction with aniline, followed by hydrogenation to produce threonine ethyl ester, and finally under the reaction of acetic anhydride and thionyl chloride, we can obtain DL-body.

Figure 2 is the chemical reaction route of DL-threonine produced from ethyl acetoacetate.
This information is compiled and edited by Xiao Nan of Chemicalbook.

Uses

1. Nutritional additives. Also for the preparation of amino acid infusion and comprehensive amino acid preparations.
2. Threonine is an important nutrient enhancer, being able to strengthen the grains, cakes and dairy products with similar effects of restoring human fatigue, promoting growth and development as tryptophan. In the field of medicine, due to that the structure of threonine contains hydroxyl, it has a water retention effect in human skin, can be combined with the oligosaccharide chain and play an important role in the protection of cell membranes. It can also promote phospholipid synthesis and fatty acid oxidation in vivo.