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Urocanic Aciduria
Urocanic aciduria is an autosomal recessive metabolic disorder caused by a deficiency of the enzyme urocanase. It is a secondary disorder of histidine metabolism.''Disorders of histidine metabolism.''http://www.ommbid.com/OMMBID/the_online_metabolic_and_molecular_bases_of_inherited_disease/b/abstract/part8/ch80 Symptoms and signs Urocanic aciduria is thought to be relatively benign. Although aggressive behavior and mental retardation have been reported with the disorder, no definitive neurometabolic connection has yet been established. Genetics Urocanic aciduria has an autosomal recessive inheritance pattern, which means the defective gene is located on an autosome, and two copies of the gene – one copy inherited from each parent – are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but are usually not affected by the disorder. Pathophysiology The amino acid histi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urocanic Acid
Urocanic acid is an intermediate in the catabolism of L-histidine. Metabolism It is formed from L-histidine through the action of histidine ammonialyase (also known as histidase or histidinase) by elimination of ammonium. In the liver, urocanic acid is transformed by urocanate hydratase (or urocanase) to 4-imidazolone-5-propionic acid and subsequently to glutamic acid. Clinical significance Inherited deficiency of urocanase leads to elevated levels of urocanic acid in the urine, a condition known as urocanic aciduria. An important role for the onset of atopic dermatitis and asthma has been attributed to filaggrin, a skin precursor of urocanic acid. Urocanic acid is thought to be a significant attractant of the nematode parasite '' Strongyloides stercoralis'', in part because of relatively high levels in the plantar surfaces of the feet, the site through which this parasite often enters the body. Function Urocanic acid was detected in animal sweat and skin where, among othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urocanic Acid
Urocanic acid is an intermediate in the catabolism of L-histidine. Metabolism It is formed from L-histidine through the action of histidine ammonialyase (also known as histidase or histidinase) by elimination of ammonium. In the liver, urocanic acid is transformed by urocanate hydratase (or urocanase) to 4-imidazolone-5-propionic acid and subsequently to glutamic acid. Clinical significance Inherited deficiency of urocanase leads to elevated levels of urocanic acid in the urine, a condition known as urocanic aciduria. An important role for the onset of atopic dermatitis and asthma has been attributed to filaggrin, a skin precursor of urocanic acid. Urocanic acid is thought to be a significant attractant of the nematode parasite '' Strongyloides stercoralis'', in part because of relatively high levels in the plantar surfaces of the feet, the site through which this parasite often enters the body. Function Urocanic acid was detected in animal sweat and skin where, among othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid Metabolism Disorders
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally 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 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 on nitrogen. Aliphatic amines contain only H and alkyl substituents. Aroma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recessive Disorders
A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders are the most common, the term is mostly used when discussing disorders with a single genetic cause, either in a gene or chromosome. The mutation responsible can occur spontaneously before embryonic development (a ''de novo'' mutation), or it can be inherited from two parents who are carriers of a faulty gene ( autosomal recessive inheritance) or from a parent with the disorder ( autosomal dominant inheritance). When the genetic disorder is inherited from one or both parents, it is also classified as a hereditary disease. Some disorders are caused by a mutation on the X chromosome and have X-linked inheritance. Very few disorders are inherited on the Y chromosome or mitochondrial DNA (due to their size). There are well over 6,000 known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aromatic Amino Acids
An aromatic amino acid is an amino acid that includes an aromatic ring. Among the 20 standard amino acids, the following are classically considered aromatic: phenylalanine, tryptophan and tyrosine. Although histidine contains an aromatic ring, its basic properties cause it to be predominantly classified as a polar amino acid. Chemical structure and properties Aromatic amino acids absorb ultraviolet light at a wavelength above 250 nm and produce fluorescence. This characteristic is used in quantitative analysis, notably in determining the concentrations of these amino acids in solution. This achieved through the utilization of a UV spectrophotomer and the Beer-Lambert Law equation. Most proteins will have an absorption maximum at 280 nm due to the presence of aromatic amino acids in their primary structure. However, because several aromatic amino acids exist, this method has low accuracy; in order to mitigate this issue, the desired protein must be pure, and its molar a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imidazole
Imidazole (ImH) is an organic compound with the formula C3N2H4. It is a white or colourless solid that is soluble in water, producing a mildly alkaline solution. In chemistry, it is an aromatic heterocycle, classified as a diazole, and has non-adjacent nitrogen atoms in meta-substitution. Many natural products, especially alkaloids, contain the imidazole ring. These imidazoles share the 1,3-C3N2 ring but feature varied substituents. This ring system is present in important biological building blocks, such as histidine and the related hormone histamine. Many drugs contain an imidazole ring, such as certain antifungal drugs, the nitroimidazole series of antibiotics, and the sedative midazolam. When fused to a pyrimidine ring, it forms a purine, which is the most widely occurring nitrogen-containing heterocycle in nature. The name "imidazole" was coined in 1887 by the German chemist Arthur Rudolf Hantzsch (1857–1935). Structure and properties Imidazole is a planar 5-membere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inborn Errors Of Metabolism
Inborn errors of metabolism form a large class of genetic diseases involving congenital disorders of enzyme activities. The majority are due to defects of single genes that code for enzymes that facilitate conversion of various substances ( substrates) into others (products). In most of the disorders, problems arise due to accumulation of substances which are toxic or interfere with normal function, or due to the effects of reduced ability to synthesize essential compounds. Inborn errors of metabolism are now often referred to as congenital metabolic diseases or inherited metabolic disorders. To this concept it's possible to include the new term of Enzymopathy. This term was created following the study of Biodynamic Enzymology, a science based on the study of the enzymes and their derivated products. Finally, ''inborn errors of metabolism'' were studied for the first time by British physician Archibald Garrod (1857–1936), in 1908. He is known for work that prefigured the "one gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellular metabolism generates many by-products that are rich in nitrogen and must be cleared from the bloodstream, such as urea, uric acid, and creatinine. These by-products are expelled from the body during urination, which is the primary method for excreting water-soluble chemicals from the body. A urinalysis can detect nitrogenous wastes of the mammalian body. Urine plays an important role in the earth's nitrogen cycle. In balanced ecosystems, urine fertilizes the soil and thus helps plants to grow. Therefore, urine can be used as a fertilizer. Some animals use it to mark their territories. Historically, aged or fermented urine (known as lant) was also used for gunpowder production, household cleaning, tanning of leather and dyeing of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Test
A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose test or a cholesterol test, are often grouped together into one test panel called a blood panel or blood work. Blood tests are often used in health care to determine physiological and biochemical states, such as disease, mineral content, pharmaceutical drug effectiveness, and organ function. Typical clinical blood panels include a basic metabolic panel or a complete blood count. Blood tests are also used in drug tests to detect drug abuse. Extraction A venipuncture is useful as it is a minimally invasive way to obtain cells and extracellular fluid ( plasma) from the body for analysis. Blood flows throughout the body, acting as a medium that provides oxygen and nutrients to tissues and carries waste products back to the excretory systems for dispos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histidinemia
Histidinemia is a rare autosomal recessive metabolic disorder caused by a deficiency of the enzyme histidase. Histidase is needed for the metabolism of the amino acid histidine. Although originally thought to be linked to multiple developmental disorders histidinemia is now accepted as a relatively benign disorder, leading to a reduction in the prevalence of neonatal screening procedures. Presentation Histidinemia is considered benign as most patients remain asymptomatic, early correlational evidence from the first decade of histidinemia research lead to the theory that histidinemia was associated with multiple developmental symptoms including hyperactivity, speech impediment, developmental delay, learning difficulties, and sometimes mental retardation. However, these claims were later deemed coincidental as a large subpopulation of infants that tested positive for histidinemia were found to have normal IQ and speech characteristics; as such histidinemia has since been reclass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histidase
Histidine ammonia-lyase (EC 4.3.1.3, histidase, histidinase) is an enzyme that in humans is encoded by the ''HAL'' gene. It converts histidine into ammonia and urocanic acid. Its systematic name is L-histidine ammonia-lyase (urocanate-forming). Function Histidine ammonia-lyase is a cytosolic enzyme catalyzing the first reaction in histidine catabolism, the nonoxidative deamination of L-histidine to ''trans''-urocanic acid. The reaction is catalyzed by 3,5-dihydro-5-methyldiene-4H-imidazol-4-one, 3,5-dihydro-5-methyldiene-4''H''-imidazol-4-one, an electrophilic co-factor which is formed autocatalytically by cyclization of the protein backbone of the enzyme. Pathology Mutations in the gene for histidase are associated with histidinemia and urocanic aciduria. References Further reading * * * * * * * * * External links * EC 4.3.1 {{lyase-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autosomal Recessive
In genetics, dominance is the phenomenon of one variant ( allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (''de novo'') or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes ( autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage). Since there is only one copy of the Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance such as in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
