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Microcystin
Microcystins—or cyanoginosins—are a class of toxins produced by certain freshwater cyanobacteria, commonly known as blue-green algae. Over 250 different microcystins have been discovered so far, of which microcystin-LR is the most common. Chemically they are cyclic heptapeptides produced through nonribosomal peptide synthases. Cyanobacteria can produce microcystins in large quantities during algal blooms which then pose a major threat to drinking and irrigation water supplies, and the environment at large. Characteristics Microcystins—or cyanoginosins—are a class of toxins produced by certain freshwater cyanobacteria; primarily ''Microcystis aeruginosa'' but also other ''Microcystis'', as well as members of the ''Planktothrix'', ''Anabaena'', ''Oscillatoria'' and ''Nostoc'' genera. Over 250 different microcystins have been discovered so far, of which microcystin-LR is the most common. Chemically they are cyclic heptapeptides produced through nonribosomal peptide synthase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcystin-LR
Microcystin-LR (MC-LR) is a toxin produced by cyanobacteria. It is the most toxic of the microcystins. Structure Microcystins are cyclic heptapeptides. The seven amino acids that are involved in the structure of a microcystin include a unique β-amino acid ( ADDA). It contains alanine (D-ala), D-β-methyl-isoaspartate (D-β-Me-isoAsp), and glutamic acid (D-glu). Furthermore, microcystins contain two variable residues, which make the differentiation between variants of microcystins. These two variable elements are always standard L-amino acids. In microcystin-LR these are leucine and arginine. more than 250 microcystins have been identified to date,''Structural Diversity, Characterization and Toxicology of Microcystins'', doi: 10.3390/toxins11120714 representing differences in the two variable residues and some modifications in the other amino acids. These modifications include demethylation of Masp and Mdha and methylesterification of D-Glu. Different microcystins have differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcystin-LR
Microcystin-LR (MC-LR) is a toxin produced by cyanobacteria. It is the most toxic of the microcystins. Structure Microcystins are cyclic heptapeptides. The seven amino acids that are involved in the structure of a microcystin include a unique β-amino acid ( ADDA). It contains alanine (D-ala), D-β-methyl-isoaspartate (D-β-Me-isoAsp), and glutamic acid (D-glu). Furthermore, microcystins contain two variable residues, which make the differentiation between variants of microcystins. These two variable elements are always standard L-amino acids. In microcystin-LR these are leucine and arginine. more than 250 microcystins have been identified to date,''Structural Diversity, Characterization and Toxicology of Microcystins'', doi: 10.3390/toxins11120714 representing differences in the two variable residues and some modifications in the other amino acids. These modifications include demethylation of Masp and Mdha and methylesterification of D-Glu. Different microcystins have differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nodularin
Nodularins are potent toxins produced by the cyanobacterium ''Nodularia spumigena'', among others. This aquatic, photosynthetic cyanobacterium forms visible colonies that present as algal blooms in brackish water bodies throughout the world. The late summer blooms of ''Nodularia spumigena'' are among the largest cyanobacterial mass occurrences in the world. Cyanobacteria are composed of many toxic substances, most notably of microcystins and nodularins: the two are not easily differentiated. A significant homology of structure and function exists between the two, and microcystins have been studied in greater detail. Because of this, facts from microcystins are often extended to nodularins. Nodularin-R is the predominant toxin variant, though 10 variants of nodularin have been discovered to date. Nodularins are cyclic nonribosomal pentapeptides and contain several unusual non-proteinogenic amino acids such as N-methyl-didehydroaminobutyric acid and the β-amino acid ADDA. These c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcystis Aeruginosa
''Microcystis aeruginosa'' is a species of freshwater cyanobacteria that can form harmful algal blooms of economic and ecological importance. They are the most common toxic cyanobacterial bloom in eutrophic fresh water. Cyanobacteria produce neurotoxins and peptide hepatotoxins, such as microcystin and cyanopeptolin. ''Microcystis aeruginosa'' produces numerous congeners of microcystin, with microcystin-LR being the most common. Microcystis blooms have been reported in at least 108 countries, with the production of microcystin noted in at least 79. Characteristics As the etymological derivation implies, ''Microcystis'' is characterized by small cells (of only a few micrometers diameter), which lack individual sheaths. Cells usually are organized into colonies (large colonies of which may be viewed with the naked eye) that begin in a spherical shape, but lose their coherence to become perforated or irregularly shaped over time in culture. Recent evidence suggests one of the dri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planktothrix
''Planktothrix'' is a diverse genus of filamentous cyanobacteria observed to amass in algal blooms in water ecosystems across the globe. Like all Oscillatoriales, ''Planktothrix'' species have no heterocysts and no akinetes. Planktothrix are unique because they have trichomes and contain gas vacuoles unlike typical planktonic organisms. Previously, some species of the taxon were grouped within the genus ''Oscillatoria,'' but recent work has defined Planktothrix as its own genus. A tremendous body of work on ''Planktothrix'' ecology and physiology has been done by Anthony E. Walsby, and the 55.6 kb microcystin synthetase gene which gives these organisms the ability to synthesize toxins has been sequenced. ''P. agardhii'' is an example of a type species of the genus. ''P. agardhii'' and ''P. rubescens'' are commonly observed in lakes of the Northern Hemisphere where they are known producers of potent hepatotoxins called microcystins. Habitats and niches Both ''P. agardhii'' and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcystis
''Microcystis'' is a genus of freshwater cyanobacteria that includes the harmful algal bloom-forming ''Microcystis aeruginosa''. Many members of a ''Microcystis'' community can produce neurotoxins and hepatotoxins, such as microcystin and cyanopeptolin. Communities are often a mix of toxin-producing and nonproducing isolates. Etymology The genus ''Microcystis'' derives from the Greek ''mikros'' (small) + ''kystis'' (bladder) Physical characteristics As the etymological derivation implies, ''Microcystis'' is characterized by small cells (a few micrometre, micrometers in diameter), possessing gas-filled vesicles (also lacking individual sheaths). The cells are usually organized into colonies (aggregations of which are visible with the naked eye) that begin in a spherical shape, losing coherence to become perforated or irregularly shaped over time. These colonies are bound by a thick mucilage composed of complex polysaccharide compounds, including xylose, mannose, glucose, fuc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanobacteria
Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blue-green algae, although they are not usually scientifically classified as algae. They appear to have originated in a freshwater or terrestrial environment. Sericytochromatia, the proposed name of the paraphyletic and most basal group, is the ancestor of both the non-photosynthetic group Melainabacteria and the photosynthetic cyanobacteria, also called Oxyphotobacteria. Cyanobacteria use photosynthetic pigments, such as carotenoids, phycobilins, and various forms of chlorophyll, which absorb energy from light. Unlike heterotrophic prokaryotes, cyanobacteria have internal membranes. These are flattened sacs called thylakoids where photosynthesis is performed. Phototrophic eukaryotes such as green plants perform photosynthesis in plast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Phosphatase 1
Protein phosphatase 1 (PP1) belongs to a certain class of phosphatases known as protein serine/threonine phosphatases. This type of phosphatase includes metal-dependent protein phosphatases (PPMs) and aspartate-based phosphatases. PP1 has been found to be important in the control of glycogen metabolism, muscle contraction, cell progression, neuronal activities, splicing of RNA, mitosis, cell division, apoptosis, protein synthesis, and regulation of membrane receptors and channels. Structure Each PP1 enzyme contains both a catalytic subunit and at least one regulatory subunit. The catalytic subunit consists of a 30-kD single-domain protein that can form complexes with other regulatory subunits. The catalytic subunit is highly conserved among all eukaryotes, thus suggesting a common catalytic mechanism. The catalytic subunit can form complexes with various regulatory subunits. These regulatory subunits play an important role in substrate specificity as well as compartmentalizatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
(all-S,all-E)-3-Amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-diene Acid
ADDA ((all-''S'',all-''E'')-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid) is a non-proteinogenic amino acid found in toxins made by cyanobacteria. Toxins which include this amino acid include microcystins and nodularin Nodularins are potent toxins produced by the cyanobacterium '' Nodularia spumigena'', among others. This aquatic, photosynthetic cyanobacterium forms visible colonies that present as algal blooms in brackish water bodies throughout the world. The ...s. References Non-proteinogenic amino acids {{organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PP2A
Protein phosphatase 2 (PP2), also known as PP2A, is an enzyme that in humans is encoded by the ''PPP2CA'' gene. The PP2A heterotrimeric protein phosphatase is ubiquitously expressed, accounting for a large fraction of phosphatase activity in eukaryotic cells. Its serine/threonine phosphatase activity has a broad substrate specificity and diverse cellular functions. Among the targets of PP2A are proteins of oncogenic signaling cascades, such as Raf, MEK, and AKT, where PP2A may act as a tumor suppressor. Structure and function PP2A consists of a dimeric core enzyme composed of the structural A and catalytic C subunits, and a regulatory B subunit. When the PP2A catalytic C subunit associates with the A and B subunits several species of holoenzymes are produced with distinct functions and characteristics. The A subunit, a founding member of the HEAT repeat protein family (huntington-elongation-A subunit-TOR), is the scaffold required for the formation of the heterotrimeric co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algal Bloom
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompasses many types of aquatic photosynthetic organisms, both macroscopic multicellular organisms like seaweed and microscopic unicellular organisms like cyanobacteria. ''Algal bloom'' commonly refers to the rapid growth of microscopic unicellular algae, not macroscopic algae. An example of a macroscopic algal bloom is a kelp forest. Algal blooms are the result of a nutrient, like nitrogen or phosphorus from various sources (for example fertilizer runoff or other forms of nutrient pollution), entering the aquatic system and causing excessive growth of algae. An algal bloom affects the whole ecosystem. Consequences range from the benign feeding of higher trophic levels to more harmful effects like blocking sunlight from reaching other organ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehydroalanine
Dehydroalanine (Cα,β-didehydroalanine, α,β-di-dehydroalanine, 2-aminoacrylate, or 2,3-didehydroalanine) is a dehydroamino acid. It does not exist in its free form, but it occurs naturally as a residue found in peptides of microbial origin. As an amino acid residue, it is unusual because it has an unsaturated backbone. Structure and reactivity Like most primary enamines, dehydroalanine is unstable. Dehydroalanine hydrolyze to pyruvate. ''N''-Acylated derivatives of dehydroalanine, such as peptides and related compounds, are stable. For example, methyl 2-acetamidoacrylate is the N-acetylated derivative of the ester. As a residue in a peptide, it is generated by a post translational modification. The required precursors are serine or cysteine residues, which undergo enzyme-mediated loss of water and hydrogen sulfide, respectively. Most amino acid residues are unreactive toward nucleophiles, but those containing dehydroalanine or some other dehydroamino acids are exceptions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
