Tyrosine
Tyrosine is an aromatic amino acid , can be found in a variety of proteins, and is particularly rich in casein milk protein, molecules containing phenol groups, Its structural formulais is as follows:
Tyrosine is found by Li Biqi 1846 from casein, white crystalline powder, needle-like crystals or platelets from the water. The relative density of 1.456 (20 ℃), the isoelectric point of 5.66, UV absorption capacity, at a wavelength of 274nm of maximum light absorption, capable of reducing phosphomolybdic acid-phosphotungstic acid reagent (Folin reagent). Melting point: L-body decomposition 290~295 ℃ (slow heating), decomposition (rapid heating) 314~318 ℃, the racemate 290 to 295 decomposition (slow heating), decomposition (rapid heating) 340 ℃. Soluble in water, alcohol, acid and alkali, insoluble in ether. Dextrose solution reacts with tyrosinase to be red. laevo isomer friction can emit light , when at 170 ℃ heated with the barium hydroxide solution ,it can become a racemate, ortho of the phenolic hydroxyl group of tyrosine molecule is prone to chemical reaction, when coupled with a diazonium acid ,it is orange-red substance, when coupled with boiling dilute acetic acid and sodium nitrite ,it is purple or red, yellow when coupled with nitric acid, when in sulfuric acid reacting with titanium dioxide it is dark orange. L-tyrosine is a natural body, by proteolysis, refining.
Tyrosine is a non-essential amino acid, is the material of a variety of body products, tyrosine is converted in vivo to a variety of biological substances by different metabolic pathways, such as dopamine, epinephrine, thyroxine, and melanin poppy (opium ) of papaverine. These substances and control neurotransmission and metabolism are closely related. Tyrosine Metabolism studies help to understand the pathogenesis of certain diseases. For example, urine black acid syndrome is related to tyrosine metabolic disorders, lack of urinary black acid oxidase in the patients causes tyrosine metabolite which is urine black acid can not continue to break down, when the air is discharged from the urine,it becomes black oxidation substance in the air. suffering from this disease, children's diapers exposed to air will gradually turn black, long home of urine also will be black. Albinism is also concerned with the metabolism of tyrosine, patients lacking tyrosinase makes tyrosine metabolites-3,4-dihydroxyphenylalanine impossible to form melanin so that the skin hairs are white.
non-essential amino acid
Amino acid is a derivative whose hydrogen atom of a hydrocarbon chain is substituted by amino. Amino acids are the basic structural units of proteins. Amino acids constituting natural proteins usually have 20 kinds. Except for proline, the amino acids are α-Amino acid. Its structural formula is:
According to the polar nature of side chain R groups of α-amino acid , 20 common amino acids forming protein can be divided into four groups: (1) R group of non polar amino acids. (2) R groups having polarity but are not charged . (3) R group with a positively charged amino acid. (4) R groups are negatively charged amino acids. Tyrosine and serine, threonine, belong to the same R groups of polarity but do not have charged amino acids. In addition to glycine, all the α-amino acids,α-carbon atom is an asymmetric carbon atom and therefore optically active. The optically active amino acid symbol and its size depend on the nature of the R group, and the solution pH measured . 20 amino acids Involved in protein forming, tyrosine, phenylalanine and tryptophan have a light absorption capability, which is the base of using UV spectrophotometry (at a wavelength at 280nm) to measure protein concentration.
The color reaction of the individual amino acid can be used for qualitative and quantitative analysis of these amino acids. Commonly used Mirren's reaction-when the phenol compound with Hg (NO3) 2 hot to make red, proteins containing tyrosine have this reaction; Pauly reaction-in alkaline solution, histidine and tyrosine acid conjugate with diazotized sulfonic acid to make red.
Tyrosine is an polar aromatic amino acid that has phenolic hydroxyl group. Abbreviated as Tyr, Y. It and Tryptophan, lysine belong to ketogenic,glycogenetic and non-essential amino acids. In animals it is generated by hydroxylation of phenylalanine, both of them decompose and transform through the common pathways . It can be transformed into dopamine, epinephrine, norepinephrine, thyroxine, melanin, protopine and tyramine and other bioactive substances. Human and animal bodies’ congenital deficiency of phenylalanine hydroxylase, urine black acid oxidase, tyrosinase, can lead to phenylketonuria, black uric acid disease and albinism respectively . Tyrosine decomposition products are fumaric acid and acetoacetate.
Above information from Chemicalbook Andy.
The above information is edited by the chemicalbook of Tian Ye.
Tyrosine in human metabolism
Tyrosine is an amino acid building blocks of proteins, and having a side chain having an aromatic ring of ionization, is addicted to the aqueous, tyrosine in the human and animal bodies is generated by the hydroxylation of phenylalanine, so when phenylalanine nutrition is adequate, it is non essential amino acid.
Catabolism of tyrosine is firstly catalyzed by tyrosine aminotransferase in the liver , then transform into hydroxyphenyl pyruvate, the enzyme needs coenzyme pyridoxal phosphate . Hydroxyphenyl pyruvate by hydroxyl phenylketonuria hydroxylase role, while oxidative decarboxylation and metastasis, and the benzene ring ortho hydroxylation of the side chain of pyruvate to generate the urine black acid (glyoxylic acid). The enzyme is a protein containing copper metal, needing ascorbic acid and coenzyme consume molecular oxygen. Black acid in urine in the urine black acid dioxygenase (urine black acid oxidase) catalyzes the cleavage benzene to produce maleic acid acetoacetate; enzyme is a protein ferrous metals, the reactions require oxygen molecule to be involved in . Maleic acid via the corresponding acetoacetate isomerase role into fumarylacetoacetate need coenzyme glutathione. Finally, from the corresponding hydrolase hydrolyzed as fumaric acid and acetyl acid, so tyrosine is both glycogeneticr and ketogenic amino acids.
tyrosine kinase
tyrosine kinase , enzyme catalytic in peptide chain tyrosine residue (loci) phosphorylated,plays an important role in biological metabolism and cell communication, and molecular weight of 56,000, endometrial bound enzyme. The enzyme consists of two domains, a catalytic domain, accounting for most of the enzyme molecules, which contains two tyrosine phosphorylation sites and a C-terminal ; the other is the regulatory domain (i.e. SH2 domain), containing the N-terminal myristoylation, serine phosphorylation site and homologous regions.
Tyrosine phosphorylation sites of the catalytic domain shows a great relation to tyrosine kinase activity , if these sites are phosphorylated, tyrosinekinase activity would be inhibited; on the contrary, if the phosphorylation of tyrosyl acid sites with phosphatase to dephosphorylate, the kinase activity can be significantly increased. Tyrosine phosphorylation sites near the ends of the C, but with different tyrosine kinase gene expression (e.g., c-src gene product family), the location of these sites is different, if it is missing out, it kinases is Activated. In addition, the polyomavirus middle T-antigen gene expression and c-src tyrosine kinase binding sites in the vicinity of 527 tyrosine at the site, since it is too close to this site , the formation of a steric hinders the phosphorylation site, it increases the kinase activity.
SH2 domain in addition to homologous regions , other parts are of the large differences in structure, so it is possible to act with different regulating factors, plays a role in regulating the kinase activity.
Tyrosine iodide
Tyrosine iodide refers to an iodine compound that activated iodide replaces the three and five proton of benzene ring of tyrosine . Iodide process is mainly carried out on the thyroglobulin molecule acinar cavity near the top of the cell site.
Tyrosine iodide and T4, T3 synthesis following steps: tyrosine firstly reacts with iodide generating a mono-iodotyrosine(MIT) and diiodo tyrosine (DIT) , two molecules of DIT are connected to generate T4. T3 is mainly in the surrounding tissue deiodination generated by the T4, but in the epithelial cells may also be generated by one molecule of MIT and DIT connection(see figure below):
In epithelial cells, the above iodide reaction is carried out on the thyroglobulin molecule tyrosine residue, not in the presence of free tyrosine . Therefore, thyroid hormone synthesis is carried out in the thyroglobulin molecule. Thyroglobulin Is a glycoprotein , thyroglobulin in the human body is composed of four polypeptide , each polypeptide chain molecular weight 160 000, , there are two forms of the polymerization of four polypeptide chains: one is four polypeptide chain dicarboxylic mutual sulfur linkage; the other is in the first two disulfide linked polypeptide chains become dimers, which then covalently linked. Three-dimensional structural integrated tetramer of thyroglobulin molecule must be completed in order to make certain tyrosine residues have proper spatial position in order to iodide, and so as to make iodinated tyrosine combine into TH. Each molecule of thyroglobulin contains about 120 tyrosine residues , few tyrosine is iodinated . It is found that thyroglobulin molecules MIT and T3 relatively increase in rats, which may be a compensatory action to cope with iodine deficiency. Synthesis of T3 requires 1/4 iodine less than the synthesis of T4 , while the activity of T3 is greater than T4. Because the thyroglobulin molecule T4/T3 ratio of 12, and day T4, T3secretion rate ratio is 3,it is Visible that inside the thyroid T4 can be converted into T3.
Reference: China Medical Encyclopedia Editing Committee; Zhang Changying editor of Chinese Medical Encyclopedia seventeen biochemistry.
Neuropeptide tyrosine
Neuropeptide tyrosine was a abiologically active polypeptide separated and purified in 1982 by the United States Tatemoto ,consisting of 36 amino acids, its structure are similar to pancreatic polypeptide, peptidesilk, it belongs to a family of peptides. Neuropeptide tyrosine genes consist of 7200 base pairs, contain four exons and five introns, can be transcribed, expressed neuropeptide tyrosine precursor containing 97 amino acids. It is mainly distributed in the central and peripheral nervous system, cardiovascular system, there is also rich in nerve fibers having a neuropeptide tyrosine. In the peripheral nervous system,it is mainly coexist with norepinephrine in sympathetic nervesand is released by the sympathetic nerve endings; in the cardiovascular system, neuropeptide tyrosine neurons are mainly in the atria, ventricles, and coronary sinus around; in the blood vessels, neuropeptide tyrosine aremainly in the arterial system, venous system are less distributed. Neuropeptide Tyrosine is one of the strong vasoconstrictor substance in the body , has a very strong and fast and lasting effect on coronary, femoral artery contraction cerebral artery, superior mesenteric artery, pulmonary artery and portal vein. Neuropeptide tyrosine is a regulatory matter, after intravenous injection can inhibit the effect of slow heart rate caused by the role of nervous excitement for a long time . Neuropeptide tyrosine mechanism is not yet understood, some people think it may be related to adenylate cyclase and G-protein activation; it is reported it has significantly depolarization on vascular smooth muscle cells. Neuropeptide tyrosine release may be associated with myocardial ischemia, cerebral vasospasm, the incidence of hypertension related. In 1989 Scott found that, after intraventricular injection,it not only did not increase blood pressure, but lower, it pointed out that such a role was the role of neuropeptide tyrosine in the brain stem, inhibiting sympathetic efferent impulses.
Melanin
Melanin Is a nitrogen-containing melanosomes , is especially distributed in skin, hair,the choroid layer, produced by the melanocytes. Tyrosine is a prerequisite for the synthesis of melanin, in tyrosinase ,firstly hydroxylate tyrosine into dopa (3,4 dihydroxyphenylalanine), following the dopa into dopa quinone. Tyrosinase is an enzyme that catalyzes the synthesis of melanin enzyme, is a copper-containing phenol oxidase. From dopa quinone reaction ,the following reactions are carried out automatically, mainly draw indole quinone through the side chains reaction, followed by aggregation, to synthesize melanin. Actually melanin must be combined with proteins and phospholipids to form a so-called melanin granules to exist. Pathogenesis of albinism is due to a congenital defect of tyrosinase, which makes melanocytes lose the ability to synthesize melanin.
Identification test
Take 0.1% of the sample solution 5ml, plus ninhydrin test solution (TS-250) 1ml , heat, reddish violet appears .
Content Analysis
Accurately weigh sample through the pre-drying after 105 ℃ 2h about 400mg, move into a 250mL flask, dissolve in about 50ml of acetic acid, add 2 drops of crystal violet test solution (TS-74), with 0.1mol/L perchloric acid, titrate to blue-green endpoint. At the same time carry out a blank test, and make the necessary corrections. 0.1mol/L perchloric acid equivalent L-tyrosine (C9H11NO3) 18.12mg per mL.
Toxicity
Safe for food (FDA, §172.320,2000).
Limited use
4.3% by weight of total protein foods (FDA, §172.320,2000).
FEMA: bakery products, meat products, snack foods, condiments, seasoning flavoring products are 250mg/kg.
The maximum amount permitted of food additives maximum allowable residue limits Chinese name of the food additive Chinese name of food allowed to use the food additive function of the additive permitted maximum amount (g/kg) maximum allowable residues (g/kg)
L-Tyrosine food spices for food flavor preparation should not exceed the maximum allowable amount and the maximum allowable residues of each perfume ingredient
in the GB 2760
Chemical Properties
White needle crystal or crystalline powder, odorless, bitter taste, mp334 ℃ (decomposition) is insoluble in water (0.04%, 25 ℃), insoluble in ethanol, ether and acetone, soluble in dilute acid or base . The isoelectric point of 5.66.
Uses
For biochemical research,it is used as amino acids nutritional in medicine for the treatment of polio, encephalitis, hyperthyroidism and other diseases.
Nutritional supplements. for the manufacture of L-dopa diiodo tyrosine. After aminocarbonyl hot reaction with sugars, it can generate a special flavor substances.
For tissue culture (L-tyrosine· 2Na· H2O), biochemical reagents, treatment of hyperthyroidism. Also available as modulation for rhe eldee, children's food and nutrition agents of plant leaves.
Production Method
after precipitation of the casein, silk and other protein acid hydrolyzates,dissolve in dilute aqueous ammonia, with acetic acid neutralize to pH = 5, recrystallization to derive it. Extract The pig hydrolyzate to get second crude liquid crystalline pure cystine, store two days at 20 ℃, tyrosine precipitation, filtration, available tyrosine crude, refine also to receive L-Tyrosine . 1% Of pig yield.
Casein as raw materials, reflux for several in hourshydrochloric acid , filter, and concentrate, soda and charcoal, crystallize,obtain products.
Production of L-Tyrosine mainly takes proteolysis extraction. blood meal, hoof angle, silk and other raw materials, acid hydrolysis, separation and purification.
Blood meal [HCl (hydrolysis)] → [110 ℃, 24h] hydrolyzate [rush acid] → [concentrated by evaporation] In addition to the acid [charcoal] → destaining solution [bleaching, cooling and crystallization] → L-Tyrosine crude [Activated Carbon (refined)] → [90 ℃, 30min] filtrate [crystalline] → L-tyrosine.
Hydrolysis, rush acid the blood meal, water, industrial hydrochloric as 1: 1.3: 1 ratio by weight, respectively put into the hydrolyzed cylinder, heat to 112-114 ℃, stop after 24h of stirring under reflux , cool and filter to remove, give filtrate which is hydrolyzate . The hydrolyzate is concentrated by evaporation to a syrup, add water to dissolve ,oncentrated by evaporation, so repeat three times to rush the acid.
Bleaching, crystallized concentrate is diluted with distilled water to the whole solution,add aqueous ammonia solution to pH 3.5, 1% charcoal is added, boiling with stirring 10min, stirring in a water bath at 90 ℃ incubated 30min, filter while hot, active carbon layer is washed with distilled water 3 times, and the filtrate and washings are combined. According to the Act, continue to use active carbon to make the solution pale yellow. The filtrate is placed in quiet place below 10 ℃ 24h, ie, crystalline precipitation, filtration to obtain crude L-tyrosine.
Recrystallized tyrosine crude 1:20 distilled water is added, after the whole solution, plus 1% activated carbon, 90 ℃ insulation mixing 30min, filter hot and the filtrate cool to refined crystallize . The crystals are collected by filtration, washed with anhydrous ethanol twice, 60 ℃ drying, the finished product is L-tyrosine.
Chemical Properties
White to off-white powder
Chemical Properties
L-Tyrosine is odorless and has a bland taste. L-Tyrosine is a nonessential amino acid, as it is synthesized in the human
body from phenylalanine. It is a precursor to epinephrine, norepinephrine and dopamine, three important neurotransmitters.
Occurrence
Reported found in white bread, macaroni, egg noodles, corn flakes, corn grits, oatmeal, wheat bran, wheat
flakes, shredded wheat, barley brown rice, rye flour, whole grain wheat flour, buttermilk, blue cheese, cheddar cheese, cottage cheese,
cream cheese, parmesan cheese, bacon, cured ham, frankfurters, pork sausage, canned red kidney beans, canned sweet corn, canned
peas, canned lima beans, canned potatoes, almonds, cashews, peanuts, dates, beef, lamb, veal, chicken and turkey.
Uses
L-Tyrosine is one of the 22 proteinogenic amino acids that are used by cells to synthesize proteins. L-Tyrosine is biologically converted from L-phenylalanine and is in turn is converted to L-DOPA and
further converted into the neurotransmitters: dopamine, norepinephrine, and epinephrine.
Uses
neuromuscular blocker
Uses
tyrosine is an amino acid. Cutaneous applications may produce an extra reserve of tyrosine in the skin, assisting or “activating” melanin synthesis. This in turn should increase and prolong the effect of the tanning process. Tyrosine’s effect is improved if the product contains vitamin B (riboflavin) plus an additional compound referred to chemically as ATP (adenosine triphosphate). experiments conducted with l-tyrosine in the form of watersoluble derivatives found that it penetrates the epidermis to the basal layer where the melanocytes are located. It is used in suntan accelerators and in skin-bronzing cosmetics to accelerate the tanning process.
Definition
ChEBI: An optically active form of tyrosine having L-configuration.
Aroma threshold values
Detection: >10 ppm
Biochem/physiol Actions
L-Tyrosine consists of a polar side chain and is a non-essential amino acid. It is utilized by cells to synthesize proteins that are involved in signal transduction. L-Tyrosine acts as a receiver of phosphate groups that are transferred by kinases.
Safety Profile
An experimental
teratogen. Experimental reproductive
effects. When heated to decomposition it
emits acrid smoke and irritating fumes.
Purification Methods
Likely impurities are L-cysteine and the ammonium salt. L-Tyrosine is dissolved in dilute ammonia, then crystallised by adding dilute acetic acid to pH 5. Also, crystallise it from H2O or EtOH/H2O, and dry it at room temperature in a vacuum over P2O5. It sublimes at 235-240o/0.03mm with 99.2% recovery and unracemised [Gross & Gradsky J Am Chem Soc 77 1678 1955]. [Albert Biochem J 50 690 1952, Greenstein & Winitz The Chemistry of the Amino Acids J. Wiley, Vol 3 pp 2348-2366 1961, Beilstein 14 IV 2264.]
