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Acetolactate Synthase
The acetolactate synthase (ALS) enzyme (also known as acetohydroxy acid or acetohydroxyacid synthase, abbr. AHAS) is a protein found in plants and micro-organisms. ALS catalyzes the first step in the synthesis of the branched-chain amino acids (valine, leucine, and isoleucine). A human protein of yet unknown function, sharing some sequence similarity with bacterial ALS, is encoded by the ILVBL (ilvB-like) gene. Structure Gene Human ILVBL gene has 17 exons resides on chromosome 19 at q13.1. Protein The catalytic peptide of ALS in ''Arabidopsis thaliana'' (mouse-eared cress) is a chloroplastic protein consisting of 670 residues, the last 615 of which form the active form. Three main domains are found, with two thiamine pyrophosphate sandwiching a DHS-like NAD/FAD-binding domain. In SCOP assignment, these subunits are named d1yhya1, d1yhya2, and d1yhya3 from the N-terminal to the C-terminal. The structure of acetolactate synthase that was used for the picture on this page wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabidopsis Thaliana
''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small plant from the mustard family (Brassicaceae), native to Eurasia and Africa. Commonly found along the shoulders of roads and in disturbed land, it is generally considered a weed. A winter annual with a relatively short lifecycle, ''A. thaliana'' is a popular model organism in plant biology and genetics. For a complex multicellular eukaryote, ''A. thaliana'' has a relatively small genome of around 135 Base pair#Length measurements, megabase pairs. It was the first plant to have its genome sequenced, and is an important tool for understanding the molecular biology of many plant traits, including flower development and phototropism, light sensing. Description ''Arabidopsis thaliana'' is an annual plant, annual (rarely biennial plant, biennial) plant, usually growing to 20–25 cm tall. The leaf, leaves form a rosette at the base of the plant, with a few leaves also on the flowering Plant ste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herbicide
Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page for EPA reports on pesticide use ihere Selective herbicides control specific weed species while leaving the desired crop relatively unharmed, while non-selective herbicides (sometimes called "total weed killers") kill plants indiscriminately. The combined effects of herbicides, nitrogen fertilizer, and improved cultivars has increased yields (per acre) of major crops by three to six times from 1900 to 2000. In the United States in 2012, about 91% of all herbicide usage, was determined by weight applied, in agriculture. In 2012, world pesticide expenditures totaled nearly US$24.7 billion; herbicides were about 44% of those sales and constituted the biggest portion, followed by insecticides, fungicides, and fumigants. Herbicide is also used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme Inhibitor
An enzyme inhibitor is a molecule that binds to an enzyme and blocks its Enzyme activity, activity. Enzymes are proteins that speed up chemical reactions necessary for life, in which Substrate (biochemistry), substrate molecules are converted into Product (chemistry), products. An enzyme Enzyme catalysis, facilitates a specific chemical reaction by binding the substrate to its active site, a specialized area on the enzyme that accelerates the Rate-determining step, most difficult step of the reaction. An enzyme inhibitor stops ("inhibits") this process, either by binding to the enzyme's active site (thus preventing the substrate itself from binding) or by binding to another site on the enzyme such that the enzyme's catalysis of the reaction is blocked. Enzyme inhibitors may bind Reversible reaction, reversibly or irreversibly. Irreversible inhibitors form a Covalent bond, chemical bond with the enzyme such that the enzyme is inhibited until the chemical bond is broken. By cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leucine-responsive Protein
Leucine responsive protein, or Lrp, is a global regulator protein, meaning that it regulates the biosynthesis of leucine, as well as the other branched-chain amino acids, valine and isoleucine. In bacteria, it is encoded by the ''lrp'' gene. Lrp alternatively activates and represses the expression of acetolactate synthase's (ALS) several isoenzymes. Lrp, in E. coli, along with DAM plays a role in the regulation of the fim operon, a group of genes needed for successful synthesis and trafficking of Type I Pili. These hair like structures are important virulence factors for different pathogenic strains of Bacteria as they can mediate biofilm formation and adhesion to host epithelia. Other examples include Salmonella enterica serovar Typhimurium and Klebsiella pneumoniae. More generally, Lrp facilitates the proliferation and pathogenesis of bacteria in their hosts. Lrp in E. coli Lrp plays a crucial role as a significant regulator in E. coli ''Escherichia coli'' ( )Wells ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ketol-acid Reductoisomerase
In enzymology, a ketol-acid reductoisomerase () is an enzyme that catalyzes the chemical reaction :(R)-2,3-dihydroxy-3-methylbutanoate + NADP+ \rightleftharpoons (S)-2-hydroxy-2-methyl-3-oxobutanoate + NADPH + H+ Thus, the two substrates of this enzyme are (R)-2,3-dihydroxy-3-methylbutanoate and NADP+, whereas its 3 products are (S)-2-hydroxy-2-methyl-3-oxobutanoate, NADPH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (R)-2,3-dihydroxy-3-methylbutanoate:NADP+ oxidoreductase (isomerizing). Other names in common use include dihydroxyisovalerate dehydrogenase (isomerizing), acetohydroxy acid isomeroreductase, ketol acid reductoisomerase, alpha-keto-beta-hydroxylacyl reductoisomerase, 2-hydroxy-3-keto acid reductoisomerase, acetohydroxy acid reductoisomerase, acetolactate reductoisomerase, dihydroxyisovalerate (isomerizing) dehydrogen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (biology)
Transcription is the process of copying a segment of DNA into RNA for the purpose of gene expression. Some segments of DNA are transcribed into RNA molecules that can encode proteins, called messenger RNA (mRNA). Other segments of DNA are transcribed into RNA molecules called non-coding RNAs (ncRNAs). Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a Complementarity (molecular biology), complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, Antiparallel (biochemistry), antiparallel RNA strand called a primary transcript. In virology, the term transcription is used when referring to mRNA synthesis from a viral RNA molecule. The genome of many Orthornavirae, RNA viruses is composed of Sense (molecular biology), negative-sense RNA which acts as a template for positive sense viral messenger RNA - a necessary step in the synthesis of viral proteins needed for viral replication. This process ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcriptional Attenuation
In genetics, attenuation is a regulatory mechanism for some bacterial operons that results in premature termination of transcription. The canonical example of attenuation used in many introductory genetics textbooks, is ribosome-mediated attenuation of the ''trp'' operon. Ribosome-mediated attenuation of the ''trp'' operon relies on the fact that, in bacteria, transcription and translation proceed simultaneously. Attenuation involves a provisional stop signal (attenuator), located in the DNA segment that corresponds to the leader sequence of mRNA. During attenuation, the ribosome becomes stalled (delayed) in the attenuator region in the mRNA leader. Depending on the metabolic conditions, the attenuator either stops transcription at that point or allows read-through to the structural gene part of the mRNA and synthesis of the appropriate protein. Attenuation is a regulatory feature found throughout Archaea and Bacteria causing premature termination of transcription.Merino E, Ya ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Threonine Ammonia-lyase
Threonine ammonia-lyase (EC 4.3.1.19, systematic name L-threonine ammonia-lyase (2-oxobutanoate-forming), also commonly referred to as threonine deaminase or threonine dehydratase, is an enzyme responsible for catalysis, catalyzing the conversion of L-threonine, L-threonine into alpha-ketobutyric acid, α-ketobutyrate and ammonia: :L-threonine = 2-oxobutanoate + NH3 (overall reaction) ::(1a) L-threonine = 2-aminobut-2-enoate + H2O ::(1b) 2-aminobut-2-enoate = 2-iminobutanoate (spontaneous) ::(1c) 2-iminobutanoate + H2O = 2-oxobutanoate + NH3 (spontaneous) α-Ketobutyrate can be converted into L-isoleucine, so threonine ammonia-lyase functions as a key enzyme in Branched-chain amino acid, BCAA chemical synthesis, synthesis. It employs a pyridoxal phosphate, pyridoxal-5'-phosphate cofactor (biochemistry), cofactor, similar to many enzymes involved in amino acid metabolism. It is found in bacteria, yeast, and plants, though most research to date has focused on forms of the enzyme in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dihydroxy-acid Dehydratase
The enzyme dihydroxy-acid dehydratase () catalyzes the chemical reaction :2,3-dihydroxy-3-methylbutanoate \rightleftharpoons 3-methyl-2-oxobutanoate + H2O This enzyme participates in valine, leucine and isoleucine biosynthesis and pantothenate and coenzyme A (CoA) biosynthesis. Nomenclature This enzyme belongs to the family of lyases, specifically the hydro-lyases, which cleave carbon-oxygen bonds. The systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivi ... of this enzyme class is 2,3-dihydroxy-3-methylbutanoate hydro-lyase (3-methyl-2-oxobutanoate-forming). Other names in common use include * acetohydroxyacid dehydratase, * α,β-dihydroxyacid dehydratase, * 2,3-dihydroxyisovalerate dehydratase, * α,β-dihydroxyisovalerate dehydratase, * dihydroxy acid dehydrase, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Branched-chain-amino-acid Transaminase
Branched-chain amino acid aminotransferase (BCAT), also known as branched-chain amino acid transaminase, is an aminotransferase enzyme which acts upon branched-chain amino acids (BCAAs). It is encoded by the ''BCAT2'' gene in humans. The BCAT enzyme catalyzes the conversion of BCAAs and α-ketoglutarate into branched chain α-keto acids and glutamate. The structure to the right of branched chain amino acid aminotransferase was found using X-ray diffraction with a resolution of 2.20 Å. The branched-chain amino acid aminotransferase found in this image was isolated from mycobacteria. This protein is made up of two identical polypeptide chains, totaling 372 residues. The biological function of branched-chain amino acid aminotransferases is to catalyse the synthesis or degradation of the branched chain amino acids leucine, isoleucine, and valine. In humans, branched chain amino acids are essential and are degraded by BCATs. Structure and function In humans, BCATs are homodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operon
In genetics, an operon is a functioning unit of DNA containing a cluster of genes under the control of a single promoter. The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo splicing to create monocistronic mRNAs that are translated separately, i.e. several strands of mRNA that each encode a single gene product. The result of this is that the genes contained in the operon are either expressed together or not at all. Several genes must be ''co-transcribed'' to define an operon. Originally, operons were thought to exist solely in prokaryotes (which includes organelles like plastids that are derived from bacteria), but their discovery in eukaryotes was shown in the early 1990s, and are considered to be rare. In general, expression of prokaryotic operons leads to the generation of polycistronic mRNAs, while eukaryotic operons lead to monocistronic mRNAs. Operons are also found in viruses such as bacteriophages. For ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
