Alpha-aminoadipic semialdehyde synthase, mitochondrial
Alpha-aminoadipic semialdehyde synthase is an enzyme encoded by the AASS gene in humans and is involved in their major lysine degradation pathway. It is similar to the separate enzymes coded for by the LYS1 and LYS9 genes in yeast, related to, although not similar in structure, the bifunctional enzyme found in plants. In humans, mutations in the AASS gene, the corresponding alpha-aminoadipic semialdehyde synthase enzyme are associated with familial hyperlysinemia; this condition is inherited in an autosomal recessive pattern and is not considered a negative condition, thus making it a rare disease. The alpha-aminoadipic semialdehyde synthase protein catalyzes the first two steps in the mammalian L-lysine degradation via saccharopine pathway within the mitochondria, thought to be the main metabolic route for lysine degradation in upper eukaryotes; the specific subpathway that this enzyme focuses on is the synthesis of glutaryl-CoA from L-lysine. Glutaryl-CoA can act as an intermediate in a more expanded conversion/degradation pathway from L-lysine to acetyl-CoA.
Two noticeable components of the L-lysine degradation via saccharopine pathway are the intermediately-used reaction/product glutamate and the eventual carbon-sink acetyl-CoA. Glutamate is an important compound within the body which acts as a neurotransmitter tied to learning and Huntington's disease. Acetyl-CoA is arguably of an higher level of importance, acting as one of the integral components of the Citric Acid/Kreb cycle, with the primary function of delivering an acetyl group to be oxidized for energy production. Thus, the function of alpha-aminoadipic semialdehyde synthase is tied to the levels of two integral compounds within the body. First, the N-terminal portion of this enzyme which contains lysine-ketoglutarate reductase activity condenses lysine and 2-oxoglutarate to a molecule called saccharopine; the C-terminal portion of this enzyme, which contains saccharopine dehydrogenase activity, catalyzes the oxidation of saccharopine to produce alpha-aminoadipic semialdehyde and glutamate.
Note: These reactions are the reverse of the corresponding steps in the lysine biosynthesis pathways present in yeast and fungi. These reactions can be visualized as well in reaction equation form: N--L-lysine + NADP+ + H2O = L-lysine + 2-oxoglutarate + NADPH followed by N--L-lysine + NAD+ + H2O = L-glutamate + -2-amino-6-oxohexanoate + NADH; the native human enzyme is bifunctional, much like the LKR/SHD found in plants, thus, is thought to be similar in structure. The bifunctionality of this enzyme comes from the fact that it contains two distinct active sites, one at its C-terminal, one at its N-terminal; the C-terminal portion of alpha-aminoadipic semialdehyde synthase contains the SHD activity and the N-terminal portion contains LKR. To date, a structure of alpha-aminoadipic semialdehyde synthase has not been determined; the enzyme does not have linker region present in plants between its C and N-termini, so theories suggest the actual structure contains an LKR-activity region bound to an SHD-activity region, like that in Magnaporthe grisea.
Alpha-aminoadipic semialdehyde synthase is encoded for by the AASS gene, mutations in this gene lead to hyperlysinemia. This is characterized by impaired breakdown of lysine which results in elevated levels of lysine in the blood and urine; these increased levels of lysine do not appear to have any negative effects on the body. Other names for this condition include: alpha-aminoadipic semialdehyde deficiency disease familial hyperlysinemia lysine alpha-ketoglutarate reductase deficiency disease saccharopine dehydrogenase deficiency disease saccharopinuriaHyperlysinemia is characterized by elevated plasma lysine levels that exceed 600 μmol/L and can reach up to 2000 μmol/L; these increased levels of lysine do not appear to have any negative effects on the body. The main reason for this is. First, lysine can be used in place of ornithine in the urea cycle resulting in the production of homoarginine. Additionally though most mammals use the saccharopine pathway for most lysine degradation, the brain has an alternative pathway which goes through an L-pipecolic acid intermediate - both of these can be seen in the figure.
It is important to note that Path 1 takes place in the mitochondria while Path 2 takes places in the peroxisome. Looking at other key enzymes within the L-lysine degradation pathway, ALDH7A1 is deficient in children with pyridoxine-dependent seizures. GCDH is deficient in glutaric aciduria type 1; the intermediate 2-oxoadipate is metabolized by 2-oxoadipate dehydrogenase, resembling the Citric Acid/Kreb cycle enzyme complex 2-oxoglutarate dehydrogenase. Two types of familial hyperlysinemia have been described so far: type I is associated with a combined deficiency of the two enzyme activities, LOR and SDH, whereas in familial hyperlysinemia type II only the saccharopine dehydrogenase activity is impaired. Type II hyperlysinemia is referred to as saccharopinuria. An additional condition shown to be related to hyperlysinemia is dienoyl-CoA reductase deficiency, though this is a recent discovery and there are not many publications supporting this. AASS human gene location in the UCSC Genome Browser.
AASS human gene details in the UCSC Genome Browser
Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. In vertebrates, it is composed of blood cells suspended in blood plasma. Plasma, which constitutes 55% of blood fluid, is water, contains proteins, mineral ions, carbon dioxide, blood cells themselves. Albumin is the main protein in plasma, it functions to regulate the colloidal osmotic pressure of blood; the blood cells are red blood cells, white blood cells and platelets. The most abundant cells in vertebrate blood are red blood cells; these contain hemoglobin, an iron-containing protein, which facilitates oxygen transport by reversibly binding to this respiratory gas and increasing its solubility in blood. In contrast, carbon dioxide is transported extracellularly as bicarbonate ion transported in plasma. Vertebrate blood is bright red when its hemoglobin is oxygenated and dark red when it is deoxygenated.
Some animals, such as crustaceans and mollusks, use hemocyanin to carry oxygen, instead of hemoglobin. Insects and some mollusks use a fluid called hemolymph instead of blood, the difference being that hemolymph is not contained in a closed circulatory system. In most insects, this "blood" does not contain oxygen-carrying molecules such as hemoglobin because their bodies are small enough for their tracheal system to suffice for supplying oxygen. Jawed vertebrates have an adaptive immune system, based on white blood cells. White blood cells help to resist parasites. Platelets are important in the clotting of blood. Arthropods, using hemolymph, have hemocytes as part of their immune system. Blood is circulated around the body through blood vessels by the pumping action of the heart. In animals with lungs, arterial blood carries oxygen from inhaled air to the tissues of the body, venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled.
Medical terms related to blood begin with hemo- or hemato- from the Greek word αἷμα for "blood". In terms of anatomy and histology, blood is considered a specialized form of connective tissue, given its origin in the bones and the presence of potential molecular fibers in the form of fibrinogen. Blood performs many important functions within the body, including: Supply of oxygen to tissues Supply of nutrients such as glucose, amino acids, fatty acids Removal of waste such as carbon dioxide and lactic acid Immunological functions, including circulation of white blood cells, detection of foreign material by antibodies Coagulation, the response to a broken blood vessel, the conversion of blood from a liquid to a semisolid gel to stop bleeding Messenger functions, including the transport of hormones and the signaling of tissue damage Regulation of core body temperature Hydraulic functions Blood accounts for 7% of the human body weight, with an average density around 1060 kg/m3 close to pure water's density of 1000 kg/m3.
The average adult has a blood volume of 5 litres, composed of plasma and several kinds of cells. These blood cells consist of erythrocytes and thrombocytes. By volume, the red blood cells constitute about 45% of whole blood, the plasma about 54.3%, white cells about 0.7%. Whole blood exhibits non-Newtonian fluid dynamics. If all human hemoglobin were free in the plasma rather than being contained in RBCs, the circulatory fluid would be too viscous for the cardiovascular system to function effectively. One microliter of blood contains: 4.7 to 6.1 million, 4.2 to 5.4 million erythrocytes: Red blood cells contain the blood's hemoglobin and distribute oxygen. Mature red blood cells lack a nucleus and organelles in mammals; the red blood cells are marked by glycoproteins that define the different blood types. The proportion of blood occupied by red blood cells is referred to as the hematocrit, is about 45%; the combined surface area of all red blood cells of the human body would be 2,000 times as great as the body's exterior surface.
4,000–11,000 leukocytes: White blood cells are part of the body's immune system. The cancer of leukocytes is called leukemia. 200,000 -- 500,000 thrombocytes: Also called platelets. Fibrin from the coagulation cascade creates a mesh over the platelet plug. About 55% of blood is blood plasma, a fluid, the blood's liquid medium, which by itself is straw-yellow in color; the blood plasma volume totals of 2.7–3.0 liters in an average human. It is an aqueous solution containing 92% water, 8% blood plasma proteins, trace amounts of other materials. Plasma circulates dissolved nutrients, such as glucose, amino acids, fatty acids, removes waste products, such as carbon dioxide and lactic acid. Other important components include: Serum albumin Blood-clotting factors Immunoglobulins lipoprotein particles Various
Citric acid is a weak organic acid that has the chemical formula C6H8O7. It occurs in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms. More than a million tons of citric acid are manufactured every year, it is used as an acidifier, as a flavoring and chelating agent. A citrate is a derivative of citric acid. An example of the former, a salt is trisodium citrate; when part of a salt, the formula of the citrate ion is written as C6H5O3−7 or C3H5O3−3. Citric acid exists in greater than trace amounts in a variety of fruits and vegetables, most notably citrus fruits. Lemons and limes have high concentrations of the acid; the concentrations of citric acid in citrus fruits range from 0.005 mol/L for oranges and grapefruits to 0.30 mol/L in lemons and limes. Within species, these values vary depending on the cultivar and the circumstances in which the fruit was grown. Industrial-scale citric acid production first began in 1890 based on the Italian citrus fruit industry, where the juice was treated with hydrated lime to precipitate calcium citrate, isolated and converted back to the acid using diluted sulfuric acid.
In 1893, C. Wehmer discovered. However, microbial production of citric acid did not become industrially important until World War I disrupted Italian citrus exports. In 1917, American food chemist James Currie discovered certain strains of the mold Aspergillus niger could be efficient citric acid producers, the pharmaceutical company Pfizer began industrial-level production using this technique two years followed by Citrique Belge in 1929. In this production technique, still the major industrial route to citric acid used today, cultures of A. niger are fed on a sucrose or glucose-containing medium to produce citric acid. The source of sugar is corn steep liquor, hydrolyzed corn starch or other inexpensive sugary solutions. After the mold is filtered out of the resulting solution, citric acid is isolated by precipitating it with calcium hydroxide to yield calcium citrate salt, from which citric acid is regenerated by treatment with sulfuric acid, as in the direct extraction from citrus fruit juice.
In 1977, a patent was granted to Lever Brothers for the chemical synthesis of citric acid starting either from aconitic or isocitrate/alloisocitrate calcium salts under high pressure conditions. This produced citric acid in near quantitative conversion under what appeared to be a reverse non-enzymatic Krebs cycle reaction. In 2007, worldwide annual production stood at 1,600,000 tons. More than 50% of this volume was produced in China. More than 50% was used as an acidity regulator in beverages, some 20% in other food applications, 20% for detergent applications and 10% for related applications other than food, such as cosmetics, pharmaceutics and in the chemical industry. Citric acid was first isolated in 1784 by the chemist Carl Wilhelm Scheele, who crystallized it from lemon juice, it can exist either as a monohydrate. The anhydrous form crystallizes from hot water, while the monohydrate forms when citric acid is crystallized from cold water; the monohydrate can be converted to the anhydrous form at about 78 °C.
Citric acid dissolves in absolute ethanol at 15 °C. It decomposes with loss of carbon dioxide above about 175 °C. Citric acid is considered to be a tribasic acid, with pKa values, extrapolated to zero ionic strength, of 5.21, 4.28 and 2.92 at 25 °C. The pKa of the hydroxyl group has been found, by means of 13C NMR spectroscopy, to be 14.4. The speciation diagram shows that solutions of citric acid are buffer solutions between about pH 2 and pH 8. In biological systems around pH 7, the two species present are the citrate ion and mono-hydrogen citrate ion; the SSC 20X hybridization buffer is an example in common use. Tables compiled for biochemical studies are available. On the other hand, the pH of a 1 mM solution of citric acid will be about 3.2. The pH of fruit juices from citrus fruits like oranges and lemons depends on the citric acid concentration, being lower for higher acid concentration and conversely. Acid salts of citric acid can be prepared by careful adjustment of the pH before crystallizing the compound.
See, for example, sodium citrate. The citrate ion forms complexes with metallic cations; the stability constants for the formation of these complexes are quite large because of the chelate effect. It forms complexes with alkali metal cations. However, when a chelate complex is formed using all three carboxylate groups, the chelate rings have 7 and 8 members, which are less stable thermodynamically than smaller chelate rings. In consequence, the hydroxyl group can be deprotonated, forming part of a more stable 5-membered ring, as in ammonium ferric citrate, 5Fe2·2H2O. Citric acid can be esterified at one or more of the carboxylic acid functional groups on the molecule, to form any of a variety of mono-, di-, tri-, mixed esters. Citrate is an intermediate in the TCA cycle, a central metabolic pathway for animals and bacteria. Citrate synthase catalyzes the condensation of oxaloacetate with acetyl CoA to form citrate. Citrate acts as the substrate for aconitase and is converted into aconitic acid.
The cycle ends with regeneration of oxaloacetate. This series
Dominance in genetics is a relationship between alleles of one gene, in which the effect on phenotype of one allele masks the contribution of a second allele at the same locus. The first allele is dominant and the second allele is recessive. For genes on an autosome, the alleles and their associated traits are autosomal dominant or autosomal recessive. Dominance is a key concept in Mendelian inheritance and classical genetics; the dominant allele codes for a functional protein whereas the recessive allele does not. A classic example of dominance is the inheritance of seed shape in peas. Peas associated with allele r. In this case, three combinations of alleles are possible: RR, Rr, rr; the RR individuals have round peas and the rr individuals have wrinkled peas. In Rr individuals the R allele masks the presence of the r allele, so these individuals have round peas. Thus, allele R is dominant to allele r, allele r is recessive to allele R; this use of upper case letters for dominant alleles and lower case ones for recessive alleles is a followed convention.
More where a gene exists in two allelic versions, three combinations of alleles are possible: AA, Aa, aa. If AA and aa individuals show different forms of some trait, Aa individuals show the same phenotype as AA individuals allele A is said to dominate, be dominant to or show dominance to allele a, a is said to be recessive to A. Dominance is not inherent to either its phenotype, it is a relationship between two alleles of their associated phenotypes. An allele may be dominant for a particular aspect of phenotype but not for other aspects influenced by the same gene. Dominance differs from epistasis, a relationship in which an allele of one gene affects the expression of another allele at a different gene; the concept of dominance was introduced by Gregor Johann Mendel. Though Mendel, "The Father of Genetics", first used the term in the 1860s, it was not known until the early twentieth century. Mendel observed that, for a variety of traits of garden peas having to do with the appearance of seeds, seed pods, plants, there were two discrete phenotypes, such as round versus wrinkled seeds, yellow versus green seeds, red versus white flowers or tall versus short plants.
When bred separately, the plants always produced generation after generation. However, when lines with different phenotypes were crossed and only one of the parental phenotypes showed up in the offspring. However, when these hybrid plants were crossed, the offspring plants showed the two original phenotypes, in a characteristic 3:1 ratio, the more common phenotype being that of the parental hybrid plants. Mendel reasoned that each parent in the first cross was a homozygote for different alleles, that each contributed one allele to the offspring, with the result that all of these hybrids were heterozygotes, that one of the two alleles in the hybrid cross dominated expression of the other: A masked a; the final cross between two heterozygotes would produce AA, Aa, aa offspring in a 1:2:1 genotype ratio with the first two classes showing the phenotype, the last showing the phenotype, thereby producing the 3:1 phenotype ratio. Mendel did not use the terms gene, phenotype, genotype and heterozygote, all of which were introduced later.
He did introduce the notation of capital and lowercase letters for dominant and recessive alleles still in use today. Most animals and some plants have paired chromosomes, are described as diploid, they have two versions of each chromosome, one contributed by the mother's ovum, the other by the father's sperm, known as gametes, described as haploid, created through meiosis. These gametes fuse during fertilization during sexual reproduction, into a new single cell zygote, which divides multiple times, resulting in a new organism with the same number of pairs of chromosomes in each cell as its parents; each chromosome of a matching pair is structurally similar to the other, has a similar DNA sequence. The DNA in each chromosome functions as a series of discrete genes that influence various traits. Thus, each gene has a corresponding homologue, which may exist in different versions called alleles; the alleles at the same locus on the two homologous chromosomes may be different. The blood type of a human is determined by a gene that creates an A, B, AB or O blood type and is located in the long arm of chromosome nine.
There are three different alleles that could be present at this locus, but only two can be present in any individual, one inherited from their mother and one from their father. If two alleles of a given gene are identical, the organism is called a homozygote and is said to be homozygous with respect to that gene; the genetic makeup of an organism, either at a single locus or over all its genes collectively, is called its genotype. The genotype of an organism directly and indirectly affects its molecular and other traits, which individually or collectively are called its phenotype. At heterozygous gene loci, the two alleles interact to produce the phenotype. In complete dominance, the effect of one allele in a heterozygous genotype masks the effect of the other; the allele that mas
Inheritance is the practice of passing on property, debts and obligations upon the death of an individual. The rules of inheritance have changed over time. In law, an heir is a person, entitled to receive a share of the deceased's property, subject to the rules of inheritance in the jurisdiction of which the deceased was a citizen or where the deceased died or owned property at the time of death; the inheritance may be either under the terms of a will or by intestate laws if the deceased had no will. However, the will must comply with the laws of the jurisdiction at the time it was created or it will be declared invalid and the intestate laws apply. A person does not become an heir before the death of the deceased, since the exact identity of the persons entitled to inherit is determined only then. Members of ruling noble or royal houses who are expected to become heirs are called heirs apparent if first in line and incapable of being displaced from inheriting by another claim. There is a further concept of joint inheritance, pending renunciation by all but one, called coparceny.
In modern law, the terms inheritance and heir refer to succession to property by descent from a deceased dying intestate. Takers in property succeeded to under a will are termed beneficiaries, devisees for real property, bequestees for personal property, or legatees for money. Except in some jurisdictions where a person cannot be disinherited, a person who would be an heir under intestate laws may be disinherited under the terms of a will. Detailed anthropological and sociological studies have been made about customs of patrilineal inheritance, where only male children can inherit; some cultures employ matrilineal succession, where property can only pass along the female line, most going to the sister's sons of the decedent. Some ancient societies and most modern states employ egalitarian inheritance, without discrimination based on gender and/or birth order; the inheritance is patrilineal. The father —that is, the owner of the land— bequeaths only to his male descendants, so the Promised Land passes from one Jewish father to his sons.
If there were no living sons and no descendants of any living sons, daughters inherit. In Numbers 27:1-4, the daughters of Zelophehad of the tribe of Manasseh come to Moses and ask for their father's inheritance, as they have no brothers; the order of inheritance is set out in Numbers 27:7-11: a man's sons inherit first, daughters if no sons, brothers if he has no children, so on. In Numbers 36, some of the heads of the families of the tribe of Manasseh come to Moses and point out that, if a daughter inherits and marries a man not from her paternal tribe, her land will pass from her birth-tribe's inheritance into her marriage-tribe's. So a further rule is laid down: if a daughter inherits land, she must marry someone within her father's tribe; the tractate Baba Bathra, written during late Antiquity in Babylon, deals extensively with issues of property ownership and inheritance according to Jewish Law. Other works of Rabbinical Law, such as the Hilkhot naḥalot: mi-sefer Mishneh Torah leha-Rambam, the Sefer ha-yerushot: ʻim yeter ha-mikhtavim be-divre ha-halakhah be-ʻAravit uve-ʻIvrit uve-Aramit deal with inheritance issues.
The first abbreviated to Mishneh Torah, was written by Maimonides and was important in Jewish tradition. All these sources agree that the firstborn son is entitled to a double portion of his father's estate: Deuteronomy 21:17; this means that, for example, if a father left five sons, the firstborn receives a third of the estate and each of the other four receives a sixth. If he left nine sons, the firstborn receives each of the other eight receive a tenth. If the eldest surviving son is not the firstborn son, he is not entitled to the double portion. Philo of Alexandria and Josephus comment on the Jewish laws of inheritance, praising them above other law codes of their time, they agreed that the firstborn son must receive a double portion of his father's estate. The New Testament does not mention anything about inheritance rights: the only story mentioning inheritance is that of the Prodigal Son, but that involved the father voluntarily passing his estate to his two sons prior to his death; the topic is not discussed among doctrinal statements of various denominations or sects, leaving that to be a matter of secular concern.
The Quran introduced a number of different rights and restrictions on matters of inheritance, including general improvements to the treatment of women and family life compared to the pre-Islamic societies that existed in the Arabian Peninsula at the time. Furthermore, the Quran introduced additional heirs that were not entitled to inheritance in pre-Islamic times, mentioning nine relatives of which six were female and three wer
Glycine is an amino acid that has a single hydrogen atom as its side chain. It is the simplest amino acid, with the chemical formula NH2‐CH2‐COOH. Glycine is one of the proteinogenic amino acids, it is encoded by all the codons starting with GG. Glycine is known as a "helix breaker", due to its ability to act as a hinge in the secondary structure of proteins. Glycine is a sweet-tasting crystalline solid, it is the only achiral proteinogenic amino acid. It can fit into hydrophilic or hydrophobic environments, due to its minimal side chain of only one hydrogen atom; the acyl radical is glycyl. Glycine was discovered in 1820 by the French chemist Henri Braconnot when he hydrolyzed gelatin by boiling it with sulfuric acid, he called it "sugar of gelatin", but the French chemist Jean-Baptiste Boussingault showed that it contained nitrogen. The American scientist Eben Norton Horsford a student of the German chemist Justus von Liebig, proposed the name "glycocoll"; the name comes from the Greek word γλυκύς "sweet tasting".
In 1858, the French chemist Auguste Cahours determined. Although glycine can be isolated from hydrolyzed protein, this is not used for industrial production, as it can be manufactured more conveniently by chemical synthesis; the two main processes are amination of chloroacetic acid with ammonia, giving glycine and ammonium chloride, the Strecker amino acid synthesis, the main synthetic method in the United States and Japan. About 15 thousand tonnes are produced annually in this way. Glycine is cogenerated as an impurity in the synthesis of EDTA, arising from reactions of the ammonia coproduct. In aqueous solution, glycine itself is amphoteric: at low pH the molecule can be protonated with a pKa of about 2.4 and at high pH it loses a proton with a pKa of about 9.6. Glycine is not essential to the human diet, as it is biosynthesized in the body from the amino acid serine, in turn derived from 3-phosphoglycerate, but the metabolic capacity for glycine biosynthesis does not satisfy the need for collagen synthesis.
In most organisms, the enzyme serine hydroxymethyltransferase catalyses this transformation via the cofactor pyridoxal phosphate: serine + tetrahydrofolate → glycine + N5,N10-Methylene tetrahydrofolate + H2OIn the liver of vertebrates, glycine synthesis is catalyzed by glycine synthase. This conversion is reversible: CO2 + NH+4 + N5,N10-Methylene tetrahydrofolate + NADH + H+ ⇌ Glycine + tetrahydrofolate + NAD+ Glycine is degraded via three pathways; the predominant pathway in animals and plants is the reverse of the glycine synthase pathway mentioned above. In this context, the enzyme system involved is called the glycine cleavage system: Glycine + tetrahydrofolate + NAD+ ⇌ CO2 + NH+4 + N5,N10-Methylene tetrahydrofolate + NADH + H+In the second pathway, glycine is degraded in two steps; the first step is the reverse of glycine biosynthesis from serine with serine hydroxymethyl transferase. Serine is converted to pyruvate by serine dehydratase. In the third pathway of glycine degradation, glycine is converted to glyoxylate by D-amino acid oxidase.
Glyoxylate is oxidized by hepatic lactate dehydrogenase to oxalate in an NAD+-dependent reaction. The half-life of glycine and its elimination from the body varies based on dose. In one study, the half-life varied between 4.0 hours. The principal function of glycine is as a precursor to proteins. Most proteins incorporate only small quantities of glycine, a notable exception being collagen, which contains about 35% glycine due to its periodically repeated role in the formation of collagen's helix structure in conjunction with hydroxyproline. In the genetic code, glycine is coded by all codons starting with GG, namely GGU, GGC, GGA and GGG. In higher eukaryotes, δ-aminolevulinic acid, the key precursor to porphyrins, is biosynthesized from glycine and succinyl-CoA by the enzyme ALA synthase. Glycine provides the central C2N subunit of all purines. Glycine is an inhibitory neurotransmitter in the central nervous system in the spinal cord and retina; when glycine receptors are activated, chloride enters the neuron via ionotropic receptors, causing an Inhibitory postsynaptic potential.
Strychnine is a strong antagonist at ionotropic glycine receptors, whereas bicuculline is a weak one. Glycine is a required co-agonist along with glutamate for NMDA receptors. In contrast to the inhibitory role of glycine in the spinal cord, this behaviour is facilitated at the glutamatergic receptors which are excitatory; the LD50 of glycine is 7930 mg/kg in rats, it causes death by hyperexcitability. In the US, glycine is sold in two grades: United States Pharmacopeia, technical grade. USP grade sales account for 80 to 85 percent of the U. S. market for glycine. If purity greater than the USP standard is needed, for example for intravenous injections, a more expensive pharmaceutical grade glycine can be used. Technical grade glycine, which may or may not meet USP grade standards, is sold at a lower price for use in industrial applications, e.g. as an agent in metal complexing and finishing. USP glycine has a wide variety of uses, including as an additive in pet food and animal feed, in foods and pharmaceuticals as a sweetener/taste enhancer, or as a component of food supplements and protein drinks.
Two glycine molecules in a dipeptide form are referred to as a diglycinate. Because they use a different s
A hereditary carrier, is a person or other organism that has inherited a recessive allele for a genetic trait or mutation but does not display that trait or show symptoms of the disease. Carriers are, able to pass the allele onto their offspring, who may express the genetic if they inherit the recessive allele from both parents; the chance of two carriers having a child with the disease is 25%. This phenomenon is a direct result of the recessive nature of many genes. Queen Victoria, her daughters Princesses Alice and Beatrix, were carriers of the X-linked hemophilia gene. Both had children who continued to pass on the gene to succeeding generations of the royal houses of Spain and Russia, into which they married. Since males only have one X chromosome, males who carried the altered gene had hemophilia B. Females have two X chromosomes, so one copy of an X-linked recessive gene would cause them to be an asymptomatic carrier; these females passed it to half of their children. Up to 1 in 25 individuals of Northern European ancestry may be considered carriers of mutations that can lead to cystic fibrosis.
The disease appears only when two of these carriers have children, as each pregnancy between them will have a 25% chance of producing a child with the disease. However, it is thought that carriers of CF may be more resistant to diarrhea during typhoid fever or cholera, are therefore not asymptomatic; this resistance leads to increased fitness of the carriers, known as a heterozygote advantage, thereby increases the frequency of the altered genes in the population. Although only about 1 of every 3,000 Caucasian newborns has CF, there are more than 900 known mutations of the gene that causes CF. Current tests look for the most common mutations. Genetic testing can be used to tell if a person carries one or more mutations of the CF gene and how many copies of each mutation; the test looks at a person’s DNA, taken from cells in a blood sample or from cells that are scraped from inside the mouth. The mutations screened by the test vary according to a person's ethnic group or by the occurrence of CF in the family.
More than 10 million Americans, including 1 in 25 Caucasian Americans, are carriers of one mutation of the CF gene. CF is present in other races, though not as as in Caucasian individuals. 1 in 46 Hispanic Americans, 1 in 65 African Americans, 1 in 90 Asian Americans carry a mutation of the CF gene. Sickle cell anemia is the most common genetic disorder among African Americans in the United States. While 8% are carriers, 1 in 375 African Americans are born with the disease. Carriers are asymptomatic, but they may show symptoms at high altitudes or under oxygen-poor environments as in instances of extreme exercise. Carriers are known to be resistant to malaria, suggesting there is a heterozygote advantage in certain regions of Africa; this is a probable explanation for why the disease is most prevalent among African Americans