Metabolism of aromatic amino acids.

. NameAromatic
amino acids
including phenylalanine, tyrosine and tryptophan, phenylalanine and tyrosine structure similar, in vivo phenylalanine can be converted into tyrosine, so the merger is discussed.(i) Phenylalanine and tyrosine 1. Phenylalanine is generally first transformed into tyrosine in the body. It is catalyzed into hydroxyl by phenylalamine hyolroxylase, which is coenzyme tethydrogen. The reaction produced by the bihydrocarbons, catalyzed by the dehydroflytic acid reductase, is reduced to a four-hydrogen
compound
(Figures 7-18) with the help of NADPH-H.
7-18 Tyrosine production . The catalytic reaction of phenylalanine hydroxylase is irreversible, and the body's cobine cannot be converted to phenylalanine.. 2. Synthetic tyrosine with melanin is catalyzed by tyrosine hydroxylase (tyrosine hydroxylase) to produce 3,4 dihydroxypropanine (3,4 didhydroxyphenylalanine L-DOPA) (Doba). This enzyme is also a monooxygenase based on tethydrobial coenzyme, which is catalyzed by dopamine to produce dopamine. Dopamine hydroxygenates β carbon atoms under the catalysis of dop β amine β-
oxidase
, which produces norepinephrine. The methamphetrine is then provided by SAM to make epinephrine methylation epinephrine. Dopamine, epinephrine, and epinephrine are collectively known as catecholamines. Tyrosine hydroxylase is a speed-limiting enzyme synthesized by cerium phenolamine and regulated by feedback from the final product (Figures 7-19).
7-19 Synthesis of phenolamines in . In melanin cells, tyrosine is catalyzed by tyrosine enzymes to produce doba, which is then oxidized to produce dopamine and enter the path of synthetic melanin. The resulting doba is further cyclified and dehydrated to produce the pyridine. Melanin is a polymer of radon. If the human body lacks tyrosinease, melanin synthesis disorders, skin, hair "white", called albinism (Figure 7-20).
7-20 melanin generation . 3. Tyrosine is raw sugar and ketogenic amino acid tyrosine by trans-amino action to produce paraben acetone acid, further decomposition to produce acetylacetic acid and Yanhuso acid, so it is raw sugar and ketone amino acids.
4. Metabolic disorders are known to have many metabolic disorders in phenylalanine and tyrosine metabolism. The most important is phenyl ketonuria (PKV), caused by a lack of phenylalanine hydroxylase. Phenylalanine does not normally change into tyrosine, the body phenylalanine accumulation, and by trans-amino action to produce phenylalanine acid (partially reduced to phenyric acid) and excreted from the urine. The accumulation of phenylaric acid is toxic to the central nervous system, so the disease is associated with intellectual developmental disorders. Early detection can control the content of phenylalanine in the diet, which is beneficial to intellectual development.other metabolic disorder is uric aciduria (alkaptonuria). Tyrosine in the breakdown of metabolism to produce intermediate product uric acid, such as urinary black acid oxidase deficiency, then uric acid cleavage ring degradation is blocked, a large number of urinary black acid excreted into the urine, oxidized by air into the corresponding pair of arginine, the latter can be polymerized into black pigment. This metabolic disorder generally has no serious consequences., Parkinson's disease is a serious neurological disease caused by the degeneration of the brain's dopamine-producing function. Clinically commonly used L doba treatment, L-doba itself can not pass through the blood-brain barrier without direct efficacy, but in the corresponding
tissue
dehydrate can produce dopamine to achieve therapeutic effect. At present, by transplanting the adrenal myelin in the brain, dopamine is produced to compensate for the deficiency of dopamine in the brain, and better results are obtained.(ii) the metabolism of tryptophanis an essential amino acid. Most
protein
less in the body, the body to its intake of less, less decomposition. In addition to participating in protein synthesis, 5 serotonin (aforementioned) can also be produced by oxidizing dehydrate. And can be degraded to produce raw sugar, ketogenic components, in the process to produce a carbon unit and nicotic acid and so on.. 1. Tryptophan decomposition first opens the tyrosine ring under the action of tryptophan-2, 3-dioxygenase to produce N-Formylkynurenine. This enzyme co-base is ferride, Vit C has the effect of protecting Fe2 plus from oxidation in the co-base, it can also be said that Vit C is the activator of this enzyme. Under the role of formamidase, methyl canine urea demethylate produces forythionate and canine urea, which can participate in a carbon unit metabolism. Dog urea, on the other hand, has three different metabolic directions.(1) canine urea is mainly catalyzed by canine ureaase (Rynurenine-3-monoxygenase) to produce 3 hydroxy canine ureaine (3-hydroxykynurenine), and then by canine ureaase (kynureninase) (with PLP as coenzyme) Catalytic hydrolysis rifts out of alanine and produces 3-hydroxyphetamine (3-hydroxyanthranilate), which can be transaminated to produce acetone acid, while 3-hydrophthalate is produced by reactions such as oxidized rip rings, dehydrate, etc. to produce α ketone acetic acid, which in turn produces acetylacetic acid. Therefore, tryptophan is both raw sugar and ketone amino acids.(2) a small amount of canine urea is transaminated and shrinks to produce canine urea.(3) a small amount of acrylic is cleavaged to produce phthalates.. 2. Nicotic acid production Tryptophan decomposition metabolism of 3-hydroxy phthalates by 3-hydroxyphetamine -3,4, - plus dioxygenase (3-hydroxyanthranilate-3, 4-dioxygenase) catalytic rift ring, can produce nicotic acid, is the key component of NAD (P) plus. This is a
of
vitamins in the body.


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