L-valine is a white monoclinic crystal or crystalline powder. It is colorless plate-shaped or scaly crystal when it is re cleaned with ethanol aqueous solution. Odorless, with special bitterness. The melting point is about 315 ℃. The pH value of 5% aqueous solution is 5.5~7.0. It is stable to heat, light and air. Soluble in water (8.85g/100ml, 25 ℃), almost insoluble in ethanol and ether. Slightly soluble in ethanol, insoluble in ether. It exists in flue-cured tobacco, burley tobacco and flue gas.
It is difficult to separate from leucine. It is an essential amino acid. Nutritional supplements. L-valine can be combined with other essential amino acids to prepare amino acid infusion and comprehensive amino acid preparations. Valine (1g/kg) is added to rice cakes, and the product has sesame flavor. It can also improve the flavor of bread. Amino acid drugs. Nutritional supplement can be used as the main component of amino acid infusion and comprehensive amino acid preparation. L-valine, one of the three branched chain amino acids, is an essential amino acid, which can treat liver failure and central nervous system dysfunction.
L-valine is one of branched chain amino acids (BCAA), which cannot be synthesized by animals themselves. It must be taken from the diet to meet its nutritional needs, so it is an essential amino acid. Amino acid is the basic structural unit of protein synthesis and the precursor of other amines required for metabolism. It is an indispensable material for life. At present, there are 20 ~ 30 kinds of amino acids known, some of which can be synthesized in the human body, called non essential amino acids, some of which cannot be synthesized in the human body and must be supplemented from the outside, called essential amino acids. Mammalian cells need 12 kinds of essential amino acids: L-arginine, L-cystine, L-histidine, L-leucine, L-isoleucine, L-lysine, L-methionine, L-phenylalanine, l-threonine, L-tryptophan, L-tyrosine L-valine. These amino acids are all left-handed isomers, and some right-handed isomers of non basic amino acids may have inhibitory effects on cultured cells. L-type amino acids are easier to absorb than D-type amino acids, but there is no difference in the absorption of D and L-methionine. The body competes for the transport of amino acids, and the transport of one amino acid can be inhibited by the presence of another amino acid. For example, L-valine and L-methionine will inhibit the absorption of L-leucine. Too much lysine in the feed will inhibit the absorption of arginine. High concentration (100mm) L-valine has no effect on the absorption of L-methionine, because it can be transported through another route.
Main functions of feed additives:
1. Adding L-valine to the diet of lactating sows can improve lactation. Its mechanism is that valine can affect the synthesis of alanine and the release of muscle. The addition of valine to sow diet can increase the level of alanine in plasma to meet the demand of breast tissue for glucose raw materials, so as to improve lactation. Valine is of great significance to the production and development of mammary gland, and valine is the limiting amino acid in the protein diet of lactating sows. The lack of valine can reduce the role of lysine. Although adding lysine to the feed of lactating pigs can improve the protein quality of the diet, it also causes the lack of valine, which will affect the milk production of sows and the weight gain of piglets. When lysine level is high, valine will become the first limiting amino acid.
2. Improve the immune function of animals. Valine can promote the transformation of animal bone cells into mature T cells. Valine deficiency can reduce the levels of complement C3 and transferrin, significantly hinder the growth of thymus and peripheral lymphoid tissue, and always inhibit the growth of acidic and neutrophils. When weaned piglets lack valine, the ability to synthesize specific antibodies will be reduced. Chicks lack valine, and the antibody response to Newcastle disease virus is reduced.
3. Affect the endocrine level of animals. Studies have shown that the addition of valine to the diets of lactating sows and rats can increase the concentration of prolactin and growth hormone in plasma.
There are many synthetic methods:
One is to produce amino isobutyl alcohol from isobutyraldehyde and ammonia, then synthesize amino isobutyronitrile with hydrogen cyanide, and then hydrolyze it.
One is hydroxyisobutyronitrile synthesized from isobutyraldehyde and hydrogen cyanide, which is hydrolyzed after reacting with ammonia to produce aminoisobutyronitrile.
It can also be directly synthesized from isobutyraldehyde, sodium cyanide and ammonium chloride, and then hydrolyzed.
The yield of the above three methods is 36% - 40%. It can also be synthesized from isobutyraldehyde, sodium cyanide and ammonium carbonate, and then hydrolyzed. The yield of this method is about 49%. The racemate obtained by the synthesis method must be disassembled by racemization. There are many methods of optical disassembly, such as hydrolyzing with acyl DL amino acid enzyme, and then separating with the poor solubility of free amino acid and acylate. The strains of fermentation method are micrococcusglutamicus.paracolabacterumcoliform, Brevibacterium ammoniagenes, Escherichia coli, aerobacteriaceae, which use glucose, urea, inorganic salts and other media to produce valine (1 ~ 1.5g/100m1), all of which are L-type without optical rotation.
Fermentation method: glucose, urea, inorganic salts [Micrococcus ammonificus or Brevibacterium ammonificus] → [fermentation] L-valine. All valines produced by fermentation are L-type, and there is no need for polarimetric resolution. The strains of fermentation method are Micrococcus glutamicus, Brevibacterium ammonificus, Escherichia coli and Aerobacter. Use glucose, urea, inorganic salts and other media.