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Cobalt Chelatase
Cobalt chelatase () is an enzyme that catalyzes the chemical reaction :ATP + hydrogenobyrinic acid a,c-diamide + Co2+ + H2O \rightleftharpoons ADP + phosphate + cob(II)yrinic acid a,c-diamide + H+ The four substrates of this enzyme are ATP, hydrogenobyrinic acid a,c-diamide, Co2+, and H2O; its four products are ADP, phosphate, cob(II)yrinic acid a,c-diamide, and H+. The aerobic cobalt chelatase (aerobic cobalamin biosynthesis pathway) consists of three subunits, CobT, CobN () and CobS (). The macrocycle of vitamin B12 can be complexed with metal via the ATP-dependent reactions in the aerobic pathway (e.g., in ''Pseudomonas denitrificans'') or via ATP-independent reactions of sirohydrochlorin in the anaerobic pathway (e.g., in ''Salmonella typhimurium''). The corresponding cobalt chelatases are not homologous. However, aerobic cobalt chelatase subunits CobN and CobS are homologous to Mg-chelatase subunits BchH and BchI, respectively. CobT, too, has been found to be rem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the 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 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 catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Ion
A hydrogen ion is created when a hydrogen atom loses or gains an electron. A positively charged hydrogen ion (or proton) can readily combine with other particles and therefore is only seen isolated when it is in a gaseous state or a nearly particle-free space. Due to its extremely high charge density of approximately 2×1010 times that of a sodium ion, the bare hydrogen ion cannot exist freely in solution as it readily hydrates, i.e., bonds quickly. The hydrogen ion is recommended by International Union of Pure and Applied Chemistry, IUPAC as a general term for all ions of hydrogen and its isotopes. Depending on the electric charge, charge of the ion, two different classes can be distinguished: positively charged ions and negatively charged ions. Cation (positively charged) A hydrogen atom is made up of a nucleus with charge +1, and a single electron. Therefore, the only positively charged ion possible has charge +1. It is noted H+. Depending on the isotope in question, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Bacteria also live in symbiotic and parasitic r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerobic Organism
Aerobic means "requiring air," in which "air" usually means oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements .... Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cellular respiration * Aerobic organism, a living thing with an oxygen-based metabolism See also * Anaerobic (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Enzymes
This article lists enzymes by their classification in the International Union of Biochemistry and Molecular Biology's Enzyme Commission (EC) numbering system. * List of EC numbers (EC 5) * List of EC numbers (EC 6) :Oxidoreductases (EC 1) (Oxidoreductase) * Dehydrogenase * Luciferase * DMSO reductase :EC 1.1 (act on the CH-OH group of donors) * :EC 1.1.1 (with NAD+ or NADP+ as acceptor) ** Alcohol dehydrogenase (NAD) ** Alcohol dehydrogenase (NADP) ** Homoserine dehydrogenase ** Aminopropanol oxidoreductase ** Diacetyl reductase **Glycerol dehydrogenase ** Propanediol-phosphate dehydrogenase ** glycerol-3-phosphate dehydrogenase (NAD+) ** D-xylulose reductase **L-xylulose reductase ** Lactate dehydrogenase ** Malate dehydrogenase ** Isocitrate dehydrogenase **HMG-CoA reductase * :EC 1.1.2 (with a cytochrome as acceptor) * :EC 1.1.3 (with oxygen as acceptor) ** Glucose oxidase ** L-gulonolactone oxidase ** Thiamine oxidase ** Xanthine oxidase * :EC 1.1.4 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligase
In biochemistry, a ligase is an enzyme that can catalyze the joining (ligation) of two large molecules by forming a new chemical bond. This is typically via hydrolysis of a small pendant chemical group on one of the larger molecules or the enzyme catalyzing the linking together of two compounds, e.g., enzymes that catalyze joining of C-O, C-S, C-N, etc. In general, a ligase catalyzes the following reaction: :Ab + C → A–C + b or sometimes :Ab + cD → A–D + b + c + d + e + f where the lowercase letters can signify the small, dependent groups. Ligase can join two complementary fragments of nucleic acid and repair single stranded breaks that arise in double stranded DNA during replication. Nomenclature The common names of ligases often include the word "ligase", such as DNA ligase, an enzyme commonly used in molecular biology laboratories to join together DNA fragments. Other common names for ligases include the word "synthetase", because they are used to synthes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salmonella Typhimurium
''Salmonella enterica'' subsp. ''enterica'' is a subspecies of ''Salmonella enterica'', the rod-shaped, flagellated, aerobic, Gram-negative bacterium. Many of the pathogenic serovars of the ''S. enterica'' species are in this subspecies, including that responsible for typhoid. Serovars ''S. enterica'' subsp. ''enterica'' contains a large number of serovars which can infect a broad range of vertebrate hosts. The individual members range from being highly host-adapted (only able to infect a narrow range of species) to displaying a broad host range. A number of techniques are currently used to differentiate between serotypes. These include looking for the presence or absence of antigens, phage typing, molecular fingerprinting and biotyping, where serovars are differentiated by which nutrients they are able to ferment. A possible factor in determining the host range of particular serovars is phage-mediated acquisition of a small number of genetic elements that enable infection of a pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sirohydrochlorin
Sirohydrochlorin is a tetrapyrrole macrocyclic metabolic intermediate in the biosynthesis of sirohaem, the iron-containing prosthetic group in sulfite reductase enzymes. It is also the biosynthetic precursor to cofactor F430, an enzyme which catalyzes the release of methane in the final step of methanogenesis. Structure Sirohydrochlorin was first isolated in the early 1970s when it was shown to be the metal-free form of the prosthetic group in the ferredoxin-nitrite reductase from spinach. Its chemical identity was established by spectroscopy and by total synthesis. Biosynthesis Sirohydrochlorin is derived from a tetrapyrrolic structural framework created by the enzymes deaminase and cosynthetase which transform aminolevulinic acid via porphobilinogen and hydroxymethylbilane to uroporphyrinogen III. The latter is the first macrocyclic intermediate common to haem, chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudomonas Denitrificans
''Pseudomonas denitrificans'' is a Gram-negative aerobic bacterium that performs denitrification. It was first isolated from garden soil in Vienna, Austria. It overproduces cobalamin ( vitamin B12), which it uses for methionine synthesis and it has been used for manufacture of the vitamin. Scientists at Rhône-Poulenc Rorer took a genetically engineered strain of the bacteria, in which eight of the ''cob'' genes involved in the biosynthesis of the vitamin had been overexpressed, to establish the complete sequence of methylation and other steps in the cobalamin pathway. Based on 16S rRNA Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal ... analysis, ''P. denitrificans'' has been placed in the '' P. pertucinogena'' group. References External linksType strain of ''Pseudomonas deni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitamin B12
Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism. It is important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the circulatory system in the maturation of red blood cells in the bone marrow. Plants do not need cobalamin and carry out the reactions with enzymes that are not dependent on it. Vitamin B12 is the most chemically complex of all vitamins, and for humans, the only vitamin that must be sourced from animal-derived foods or from supplements. Only some archaea and bacteria can synthesize vitamin B12. Most people in developed countries get enough B12 from the consumption of meat or foods with animal sources. Foods containing vitamin B12 include meat, clams, liver, fish, poultry, eggs, and dairy products. Many breakfast cereals a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrocycle
Macrocycles are often described as molecules and ions containing a ring of twelve or more atoms. Classical examples include the crown ethers, calixarenes, porphyrins, and cyclodextrins. Macrocycles describe a large, mature area of chemistry. Synthesis The formation of macrocycles by ring-closure is called macrocylization. Pioneering work was reported for studies on terpenoid macrocycles. The central challenge to macrocyclization is that ring-closing reactions do not favor the formation of large rings. Instead, small rings or polymers tend to form. This kinetic problem can be addressed by using high-dilution reactions, whereby intramolecular processes are favored relative to polymerizations. Some macrocyclizations are favored using template reactions. Templates are ions, molecules, surfaces etc. that bind and pre-organize compounds, guiding them toward formation of a particular ring size. The crown ethers are often generated in the presence of an alkali metal cation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
