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Tyrosinemia Type III
Tyrosinemia type III is a rare disorder caused by a deficiency of the enzyme 4-hydroxyphenylpyruvate dioxygenase (), encoded by the gene ''HPD''. This enzyme is abundant in the liver, and smaller amounts are found in the kidneys. It is one of a series of enzymes needed to break down tyrosine. Specifically, 4-hydroxyphenylpyruvate dioxygenase converts a tyrosine byproduct called 4-hydroxyphenylpyruvate to homogentisic acid. Characteristic features of type III tyrosinemia include mild mental retardation, seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with los ...s, and periodic loss of balance and coordination ( intermittent ataxia). Type III tyrosinemia is very rare; only a few cases have been reported. References External links {{Amino acid metabolic pathology Amino acid metab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrosine
-Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid with a polar side group. The word "tyrosine" is from the Greek ''tyrós'', meaning ''cheese'', as it was first discovered in 1846 by German chemist Justus von Liebig in the protein casein from cheese. It is called tyrosyl when referred to as a functional group or side chain. While tyrosine is generally classified as a Hydrophobe, hydrophobic amino acid, it is more hydrophilic than phenylalanine. It is Genetic code, encoded by the Genetic code#Codons, codons UAC and UAU in messenger RNA. Functions Aside from being a proteinogenic amino acid, tyrosine has a special role by virtue of the phenol functionality. It occurs in proteins that are part of signal transduction processes and functions as a receiver of phosphate groups that are transferred by way of protein kinases. Phosphorylation of the hyd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-hydroxyphenylpyruvate Dioxygenase
4-Hydroxyphenylpyruvate dioxygenase (HPPD), also known as α-ketoisocaproate dioxygenase (KIC dioxygenase), is an Fe(II)-containing non-heme oxygenase that catalyzes the second reaction in the catabolism of tyrosine - the conversion of 4-hydroxyphenylpyruvate into homogentisate. HPPD also catalyzes the conversion of phenylpyruvate to 2-hydroxyphenylacetate and the conversion of α-ketoisocaproate to β-hydroxy β-methylbutyrate. HPPD is an enzyme that is found in nearly all aerobic forms of life. Enzyme mechanism HPPD is categorized within a class of oxygenase enzymes that usually utilize α-ketoglutarate and diatomic oxygen to oxygenate or oxidize a target molecule. However, HPPD differs from most molecules in this class due to the fact that it does not use α-ketoglutarate, and it only utilizes two substrates while adding both atoms of diatomic oxygen into the product, homogentisate. The HPPD reaction occurs through a NIH shift and involves the oxidative decarboxylation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-hydroxyphenylpyruvate
4-Hydroxyphenylpyruvic acid (4-HPPA) is an intermediate in the metabolism of the amino acid phenylalanine. The aromatic side chain of phenylalanine is hydroxylated by the enzyme phenylalanine hydroxylase to form tyrosine. The conversion from tyrosine to 4-HPPA is in turn catalyzed by tyrosine aminotransferase. Additionally, 4-HPPA can be converted to homogentisic acid which is one of the precursors to ochronotic pigment. It is an intermediary compound in the biosynthesis of scytonemin. See also * 4-Hydroxyphenylpyruvate dioxygenase 4-Hydroxyphenylpyruvate dioxygenase (HPPD), also known as α-ketoisocaproate dioxygenase (KIC dioxygenase), is an Fe(II)-containing non-heme oxygenase that catalyzes the second reaction in the catabolism of tyrosine - the conversion of 4-hydro ... References Natural phenols Phenols Alpha-keto acids Propionic acids Hydroxy acids {{biochem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homogentisic Acid
Homogentisic acid (2,5-dihydroxyphenylacetic acid) is a phenolic acid usually found in ''Arbutus unedo'' (strawberry-tree) honey. It is also present in the bacterial plant pathogen ''Xanthomonas campestris'' pv. ''phaseoli'' as well as in the yeast ''Yarrowia lipolytica'' where it is associated with the production of brown pigments. It is oxidatively dimerised to form hipposudoric acid, one of the main constituents of the 'blood sweat' of hippopotamuses. It is less commonly known as melanic acid, the name chosen by William Prout. Human pathology Accumulation of excess homogentisic acid and its oxide, named alkapton, is a result of the failure of the enzyme homogentisic acid 1,2-dioxygenase (typically due to a mutation) in the degradative pathway of tyrosine, consequently associated with alkaptonuria. Intermediate It is an intermediate in the catabolism of aromatic amino acids such as phenylalanine and tyrosine. 4-Hydroxyphenylpyruvate (produced by transamination of tyrosin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mental Retardation
Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation,Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by significantly impaired intellectual and adaptive functioning. It is defined by an IQ under 70, in addition to deficits in two or more adaptive behaviors that affect everyday, general living. Intellectual functions are defined under DSM-V as reasoning, problem‑solving, planning, abstract thinking, judgment, academic learning, and learning from instruction and experience, and practical understanding confirmed by both clinical assessment and standardized tests. Adaptive behavior is defined in terms of conceptual, social, and practical skills involving tasks performed by people in their everyday lives. Intellectual disability is subdivided into syndromic intellectual disability, in which intellectual deficits associated with other medical and beh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seizure
An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with loss of consciousness ( tonic-clonic seizure), to shaking movements involving only part of the body with variable levels of consciousness (focal seizure), to a subtle momentary loss of awareness ( absence seizure). Most of the time these episodes last less than two minutes and it takes some time to return to normal. Loss of bladder control may occur. Seizures may be provoked and unprovoked. Provoked seizures are due to a temporary event such as low blood sugar, alcohol withdrawal, abusing alcohol together with prescription medication, low blood sodium, fever, brain infection, or concussion. Unprovoked seizures occur without a known or fixable cause such that ongoing seizures are likely. Unprovoked seizures may be exacerbated by stress or sl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intermittent Ataxia
Intermittency is a behavior of dynamical systems: regular alternation of phases of apparently periodic and chaotic dynamics. Intermittent or intermittency may also refer to: * Intermittent river or stream, the one that ceases to flow every year or at least twice every five years * Intermittent energy source, renewable energy sources that are not dispatchable due to their fluctuating nature *Intermittent fault, malfunction of a device or system that occurs at intervals, usually irregular * Fluorescence intermittency, or blinking, is random switching between ON (bright) and OFF (dark) states *Intermittent control Intermittent control is a feedback control method which not only explains some human control systems but also has applications to control engineering. In the context of control theory, intermittent control provides a spectrum of possibilities bet ..., possibilities between the two extremes of continuous-time and discrete-time control: the control signal See also * * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid Metabolism Disorders
In chemistry, amines (, ) are chemical compound, compounds and functional groups that contain a base (chemistry), basic nitrogen atom with a lone pair. Amines are formally derivative (chemistry), derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group (these may respectively be called alkylamines and arylamines; amines in which both types of substituent are attached to one nitrogen atom may be called alkylarylamines). Important amines include amino acids, biogenic amines, trimethylamine, and aniline; Inorganic compound, Inorganic derivatives of ammonia are also called amines, such as monochloramine (). The substituent is called an amino group. Compounds with a nitrogen atom attached to a carbonyl group, thus having the structure , are called amides and have different chemical properties from amines. Classification of amines Amines can be classified according to the nature and number of substituents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
