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Molybdenum In Biology
Molybdenum is an essential element in most organisms. It is most notably present in nitrogenase which is an essential part of nitrogen fixation. Mo-containing enzymes Molybdenum is an essential element in most organisms; a 2008 research paper speculated that a scarcity of molybdenum in the Earth's early oceans may have strongly influenced the evolution of eukaryotic life (which includes all plants and animals). At least 50 molybdenum-containing enzymes have been identified, mostly in bacteria. Those enzymes include aldehyde oxidase, sulfite oxidase and xanthine oxidase. With one exception, Mo in proteins is bound by molybdopterin to give the molybdenum cofactor. The only known exception is nitrogenase, which uses the FeMoco cofactor, which has the formula Fe7MoS9C. In terms of function, molybdoenzymes catalyze the oxidation and sometimes reduction of certain small molecules in the process of regulating nitrogen, sulfur, and carbon. In some animals, and in humans, the oxidation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FeMoco
FeMoco ( cofactor) or M-cluster is the primary cofactor of nitrogenase. Nitrogenase is the enzyme that catalyzes the conversion of atmospheric nitrogen molecules N2 into ammonia (NH3) through the process known as nitrogen fixation. Because it contains iron and molybdenum, the cofactor is called FeMoco. Its stoichiometry is Fe7MoS9C. Structure The FeMo cofactor is a cluster with composition Fe7MoS9C. This cluster can be viewed as two subunits composed of one Fe4S3 ( iron(III) sulfide) cluster and one MoFe3S3 cluster. The two clusters are linked by three sulfide ligands and a bridging carbon atom. The unique iron (Fe) is anchored to the protein by a cysteine. It is also bound to three sulfides, resulting in tetrahedral molecular geometry. The additional six Fe centers in the cluster are each bonded to three sulfides. These six internal Fe centers define a trigonal prismatic arrangement around a central carbide center. The molybdenum is attached to three sulfides and is anchored ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metabolism
Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the conversion of food to building blocks of proteins, lipids, nucleic acids, and some carbohydrates; and the elimination of metabolic wastes. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their Structures#Biological, structures, and respond to their environments. The word ''metabolism'' can also refer to the sum of all chemical reactions that occur in living organisms, including digestion and the transportation of substances into and between different cells, in which case the above described set of reactions within the cells is called intermediary (or intermediate) metabolism. Metabolic reactions may be categorized as ''catabolic''—the ''breaking down'' of compounds (for example, of glucose to pyruvate by c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infertility
In biology, infertility is the inability of a male and female organism to Sexual reproduction, reproduce. It is usually not the natural state of a healthy organism that has reached sexual maturity, so children who have not undergone puberty, which is the body's start of fertility, reproductive capacity, are excluded. It is also a normal state in women after menopause. In humans, ''infertility'' is defined as the inability to become pregnant after at least one year of unprotected and regular sexual intercourse involving a male and female partner. There are many causes of infertility, including some that Assisted reproductive technology, medical intervention can treat. Estimates from 1997 suggest that worldwide about five percent of all heterosexual couples have an unresolved problem with infertility. Many more couples, however, experience involuntary childlessness for at least one year, with estimates ranging from 12% to 28%. Male infertility is responsible for 20–30% of infert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Median Lethal Dose
In toxicology, the median lethal dose, LD50 (abbreviation for " lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a given substance. The value of LD50 for a substance is the dose required to kill half the members of a tested population after a specified test duration. LD50 figures are frequently used as a general indicator of a substance's acute toxicity. A lower LD50 is indicative of higher toxicity. The term LD50 is generally attributed to John William Trevan. The test was created by J. W. Trevan in 1927. The term semilethal dose is occasionally used in the same sense, in particular with translations of foreign language text, but can also refer to a sublethal dose. LD50 is usually determined by tests on animals such as laboratory mice. In 2011, the U.S. Food and Drug Administration approved alternative methods to LD50 for testing the cosmetic drug botox without animal tests. Conventions The LD50 is usually expr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tooth Enamel
Tooth enamel is one of the four major Tissue (biology), tissues that make up the tooth in humans and many animals, including some species of fish. It makes up the normally visible part of the tooth, covering the Crown (tooth), crown. The other major tissues are dentin, cementum, and Pulp (tooth), dental pulp. It is a very hard, white to off-white, highly mineralised substance that acts as a barrier to protect the tooth but can become susceptible to degradation, especially by acids from food and drink. In rare circumstances enamel fails to form, leaving the underlying dentin exposed on the surface. Features Enamel is the hardest substance in the human body and contains the highest percentage of minerals (at 96%),Ross ''et al.'', p. 485 with water and organic material composing the rest.Ten Cate's Oral Histology, Nancy, Elsevier, pp. 70–94 The primary mineral is hydroxyapatite, which is a crystalline calcium phosphate. Enamel is formed on the tooth while the tooth develops wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitochondrial Amidoxime Reducing Component 1
Mitochondrial amidoxime-reducing component 1 (also known as MOCO sulphurase C-terminal domain containing 1, MOSC1 or MARC1) is a mammalian molybdenum-containing enzyme. It is located in the outer mitochondrial membrane and consists of a N-terminal mitochondrial signal domain facing the inter-membrane space, a transmembrane domain, and a C-terminal catalytic domain facing the cytosol. In humans it is encoded by the ''MOSC1'' gene. MOCO stands for molybdenum cofactor. MOSC1 has been reported to reduce amidoximes to amidines. Genetic variation in MARC1 has been reported to be associated with lower blood cholesterol levels, blood liver enzyme levels, reduced liver fat and protection from cirrhosis suggesting that MARC1 deficiency may protect against liver disease. A genome-wide association study involving subjects from the UK Biobank UK Biobank is a long-term prospective biobank study in the United Kingdom (UK) that houses the de-identified biological samples and health-relate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xanthine Oxidase
Xanthine oxidase (XO or XAO) is a form of xanthine oxidoreductase, a type of enzyme that generates reactive oxygen species. These enzymes catalyze the oxidation of hypoxanthine to xanthine and can further catalyze the oxidation of xanthine to uric acid. These enzymes play an important role in the catabolism of purines in some species, including humans. Xanthine oxidase is defined as an ''enzyme activity'' (EC 1.17.3.2). The same protein, which in humans has the HGNC approved gene symbol ''XDH'', can also have xanthine dehydrogenase activity (EC 1.17.1.4). Most of the protein in the liver exists in a form with xanthine dehydrogenase activity, but it can be converted to xanthine oxidase by reversible sulfhydryl oxidation or by irreversible proteolytic modification. "XDH xanthine dehydrogenase" Reaction The following chemical reactions are catalyzed by xanthine oxidase: * hypoxanthine + H2O + O2 xanthine + H2O2 * xanthine + H2O + O2 uric acid + H2O2 * Xanthine oxidase ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molybdopterin
Molybdopterins are a class of cofactors found in most molybdenum-containing and all tungsten-containing enzymes. Synonyms for molybdopterin are: MPT and pyranopterin-dithiolate. The nomenclature for this biomolecule can be confusing: Molybdopterin itself contains no molybdenum; rather, this is the name of the ligand (a ''pterin'') that will bind the active metal. After molybdopterin is eventually complexed with molybdenum, the complete ligand is usually called molybdenum cofactor. Molybdopterin is required for all forms of life. Molybdopterin consists of a pyranopterin, a complex heterocycle featuring a pyran fused to a pterin ring. In addition, the pyran ring features two thiolates, which serve as ligands in molybdo- and tungstoenzymes. In some cases, the alkyl phosphate group is replaced by an alkyl diphosphate nucleotide. Enzymes that contain the molybdopterin cofactor include xanthine oxidase, DMSO reductase, sulfite oxidase, and nitrate reductase. The only molyb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pterin
Pterin is a heterocyclic compound composed of a pteridine ring system, with a " keto group" (a lactam) and an amino group on positions 4 and 2 respectively. It is structurally related to the parent bicyclic heterocycle called pteridine. Pterins, as a group, are compounds related to pterin with additional substituents. Pterin itself is of no biological significance. Pterins were first discovered in the pigments of butterfly wings (hence the origin of their name, from the Greek ''pteron'' (), wing) and perform many roles in coloration in the biological world. Chemistry Pterins exhibit a wide range of tautomerism in water, beyond what is assumed by just keto-enol tautomerism. For the unsubstituted pterin, at least five tautomers are commonly cited. For 6-methylpterin, seven tautomers are theoretically predicted to be important in solution. The pteridine ring system contains four nitrogen atoms, reducing its aromaticity to the point that it can be attacked by nucleophi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dietary Element
In the context of nutrition, a mineral is a chemical element. Some "minerals" are essential for life, but most are not. ''Minerals'' are one of the four groups of essential nutrients; the others are vitamins, essential fatty acids, and essential amino acids. The five major minerals in the human body are calcium, phosphorus, potassium, sodium, and magnesium. The remaining minerals are called "trace elements". The generally accepted trace elements are iron, chlorine, cobalt, copper, zinc, manganese, molybdenum, iodine, selenium, and bromine; there is some evidence that there may be more. The four organogenic elements, namely carbon, hydrogen, oxygen, and nitrogen (CHON), that comprise roughly 96% of the human body by weight, are usually not considered as minerals (nutrient). In fact, in nutrition, the term "mineral" refers more generally to all the other functional and structural elements found in living organisms. Plants obtain minerals from soil. Animals ingest plants, thus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molybdenum Cofactor
A molybdenum cofactor is a biochemical Cofactor (biochemistry), cofactor that contains molybdenum. Examples include: * Molybdopterin (or, strictly speaking, the molybdopterin-molybdenum-complex), the organophosphate-dithiolate ligand that binds molybdenum and tungsten in most molybdenum- (except nitrogenases) and all tungsten-containing proteins * FeMoco, a metal cluster that contains Fe, Mo, and S that is found in some nitrogenases {{SIA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FeMoco Cluster
FeMoco ( cofactor) or M-cluster is the primary cofactor of nitrogenase. Nitrogenase is the enzyme that catalyzes the conversion of atmospheric nitrogen molecules N2 into ammonia (NH3) through the process known as nitrogen fixation. Because it contains iron and molybdenum, the cofactor is called FeMoco. Its stoichiometry is Fe7MoS9C. Structure The FeMo cofactor is a cluster with composition Fe7MoS9C. This cluster can be viewed as two subunits composed of one Fe4S3 ( iron(III) sulfide) cluster and one MoFe3S3 cluster. The two clusters are linked by three sulfide ligands and a bridging carbon atom. The unique iron (Fe) is anchored to the protein by a cysteine. It is also bound to three sulfides, resulting in tetrahedral molecular geometry. The additional six Fe centers in the cluster are each bonded to three sulfides. These six internal Fe centers define a trigonal prismatic arrangement around a central carbide center. The molybdenum is attached to three sulfides and is anchored t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
