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Phenylalanine Hydroxylase
Phenylalanine hydroxylase (PAH) () is an enzyme that catalyzes the hydroxylation of the aromatic side-chain of phenylalanine to generate tyrosine. PAH is one of three members of the biopterin-dependent aromatic amino acid hydroxylases, a class of monooxygenase that uses tetrahydrobiopterin (BH4, a pteridine cofactor) and a non-heme iron for catalysis. During the reaction, molecular oxygen is heterolytically cleaved with sequential incorporation of one oxygen atom into BH4 and phenylalanine substrate. In humans, mutations in its encoding gene, ''PAH (gene), PAH'', can lead to the metabolic disorder phenylketonuria. Enzyme mechanism The reaction is thought to proceed through the following steps: # formation of a Fe(II)-O-O-BH4 bridge. # heterolytic cleavage of the O-O bond to yield the ferryl oxo hydroxylating intermediate Fe(IV)=O # attack on Fe(IV)=O to hydroxylate phenylalanine substrate to tyrosine. Formation and cleavage of the iron-peroxypterin bridge. Although eviden ...
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Enzyme
Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are Ribozyme, catalytic RNA molecules, called ribozymes. Enzymes' Chemical ...
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Dopamine
Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical , CH4; is among the simplest organic compounds. In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, ... of the catecholamine (noradrenaline) Image:Adrenalin - Adrenaline.svg">140px, epinephrine (adrenaline) A catecholamine (; abbreviated CA) is a monoamine neurotransmitter, an organic compound that has a catechol">organic_compound.html" ;"title="monoamine neurotra ... and phenethylamine Phenethylamine (PEA) is an organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's ability to Ca ... families. Dopamine constitutes ...
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Gastrointestinal Tract
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system The human digestive system consists of the gastrointestinal tract The gastrointestinal tract, (GI tract, GIT, digestive tract, digestion tract, alimentary canal) is the tract from the mouth to the anus which includes all the organs of th ... that leads from the mouth In animal anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is ... to the anus The anus (from Latin ''wikt:en:anus#Latin, anus'' meaning "ring", "circle") is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that .... The GI tract contains all the major organ Organ may refer to: Biol ...
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Serotonin
Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter Monoamine neurotransmitters are s and s that contain one group connected to an by a two-carbon chain (such as -CH2-CH2-). Examples are , and . All monoamines are derived from aromatic s like , , and by the action of s. They are deactivated .... Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vasoconstriction. Biochemically, the indoleamine Indolamines are a family of neurotransmitter Neurotransmitters are chemical messengers that transmit a signal from a neuron across the synapse to a target cell, which can be a different neuron, muscle cell, or gland cell. Neurotransmitters ... molecule derives from the amino acid tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carbo ...
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Mass Spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio The mass-to-charge ratio (''m''/''Q'') is a physical quantity A physical quantity is a physical property of a material or system that can be Quantification (science), quantified by measurement. A physical quantity can be expressed as a ''value'', ... of ion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ...s. The results are presented as a ''mass spectrum mass spectrum of toluene Toluene (), also known as toluol (), is an aromatic hydrocarbon. It is a colorless, Water (molecule), water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, con ...'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrome ...
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Newborn Screening
Newborn screening (NBS) is a public health program of screening (medicine), screening in infants shortly after childbirth, birth for conditions that are treatable, but not clinically evident in the newborn period. The goal is to identify infants at risk for these conditions early enough to confirm the diagnosis and provide intervention that will alter the clinical course of the disease and prevent or ameliorate the clinical manifestations. NBS started with the discovery that the amino acid disorder phenylketonuria (PKU) could be treated by dietary adjustment, and that early intervention was required for the best outcome. Infants with PKU appear normal at birth, but are unable to metabolize the essential amino acid phenylalanine, resulting in irreversible intellectual disability. In the 1960s, Robert Guthrie developed a simple method using a bacterial inhibition assay that could detect high levels of phenylalanine in blood shortly after a baby was born. Guthrie also pioneered th ...
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Guthrie Test
The neonatal heel prick is a blood collection procedure done on newborns. It consists of making a pinprick puncture in one heel of the newborn to collect their blood. This technique is used frequently as the main way to collect blood from neonates. Other techniques include venous or arterial needle sticks, cord blood sampling, or umbilical line collection. This technique is often utilized for the Guthrie test, where it is used to soak the blood into pre-printed collection cards known as Guthrie cards. The classical Guthrie test is named after Robert Guthrie, an American bacteriologist and physician who devised it in 1962. The test has been widely used throughout North America and Europe as one of the core newborn screening tests since the late 1960s. The test was initially a bacterial inhibition assay, but is gradually being replaced in many areas by newer techniques such as tandem mass spectrometry that can detect a wider variety of congenital diseases. Detected diseases The b ...
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Pharmacological Chaperone
A pharmacological chaperone or pharmacoperone is a drug that acts as a chaperone (protein), protein chaperone. That is, it contains small molecules that enter cells and serve as a molecular scaffolding in order to cause otherwise-protein folding, misfolded mutant proteins to fold and route correctly within the cell. Mutation of proteins often causes molecular misfolding, which results in protein misrouting within the cell. Accordingly, mutant molecules may retain proper function but end up in parts of the cell where the function is inappropriate, or even deleterious, to cell function. Misfolded proteins are usually recognized by the quality-control system of the cell and retained (and often destroyed or recycled) in the endoplasmic reticulum. Pharmacoperones correct the folding of misfolded proteins, allowing them to pass through the cell's quality-control system and become correctly routed. Since mutations often cause disease by causing misfolding and misrouting, pharmacoperones ...
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Hyperphenylalaninemia
Hyperphenylalaninemia is a medical condition A disease is a particular abnormal condition that negatively affects the structure A structure is an arrangement and organization of interrelated elements in a material object or system A system is a group of Interaction, interactin ... characterized by mildly or strongly elevated concentrations of the amino acid phenylalanine in the blood. Phenylketonuria (PKU) can result in severe hyperphenylalaninemia. Phenylalanine concentrations ([phe]) are routinely screened in newborns by the neonatal heel prick (Guthrie test), which takes a few drops of blood from the heel of the infant. Standard [phe] concentrations in unaffected persons are about 60molar concentration, µM: [phe] concentrations in persons with untreated phenylketonuria may be many times that (600µM to 2400µM), which indicate that the child is at risk for severe intellectual disability. Phenylketonuria is classed as an autosomal recessive condition: in zygosity# ...
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Tryptophan Hydroxylase
Tryptophan hydroxylase (TPH) is an enzyme () involved in the synthesis of the neurotransmitter serotonin. Tyrosine hydroxylase, phenylalanine hydroxylase, and tryptophan hydroxylase together constitute the family of biopterin-dependent aromatic amino acid hydroxylases. TPH catalyzes the following chemical reaction : L-tryptophan + tetrahydrobiopterin + O2 \rightleftharpoons 5-Hydroxytryptophan + dihydrobiopterin + H2O It employs one additional cofactor (biochemistry), cofactor, iron. Function It is responsible for addition of the -HO group (hydroxylation) to the 5 position to form the amino acid 5-hydroxytryptophan (5-HTP), which is the initial and rate-limiting step in the synthesis of the neurotransmitter serotonin. It is also the first enzyme in the synthesis of melatonin. Tryptophan hydroxylase (TPH), tyrosine hydroxylase (TH) and phenylalanine hydroxylase (PAH) are members of a superfamily of aromatic amino acid hydroxylases, catalyzing key steps in important metabol ...
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Tyrosine Hydroxylase
-Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acid Amino acids are organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), millions of organic compounds are known. The study of the properties, reactions, a ...s that are used by cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a small room, hut, or cave in which a monk or religious recluse lives * Prison cell, a room used to hold peopl ... to synthesize proteins. It is a non-essential amino acid An essential amino acid, or indispensable amino acid, is an amino acid Amino acids are organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carb ... with a polar side group. The word "tyrosine" is ...
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