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Helper-component Proteinase
Helper-component proteinase (, ''HC-Pro'') is an enzyme. This enzyme catalyses the following chemical reaction : Hydrolyses a Gly-Gly bond at its own C-terminus, commonly in the sequence -Tyr-Xaa-Val-Gly-Gly, in the processing of the potyviral polyprotein This enzyme is present in plant RNA viruses of the '' Potyviridae'' family. HC-Pro is encoded by all potyviruses, but is absent in some members of the ''Ipomovirus ''Ipomovirus'' is a genus of positive-strand RNA viruses in the family '' Potyviridae''. Member viruses infect plants and are transmitted by whiteflies ('' Bemisia tabaci''). The name of the genus is derived from '' Ipomoea'' – the generic na ...'' genus. HC-Pro is involved in virus transmission, virus polyprotein processing, and suppression of RNA silencing, an antiviral mechanism of plants. References External links * {{Portal bar, Biology, border=no EC 3.4.22 ... [...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 substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), 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, 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 Ribozyme, catalytic RNA molecules, called ribozymes. Enzymes' Chemical specificity, specific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalysis
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usually gaseous or liquid) as the reactant, or heterogeneous, whose components are not in the same phase. Enzymes and other biocatalysts are often considered as a third category. Catalysis is ubiquitous in chemical industry of all kinds. Estimates are that 90% of all commercially produced chemical products involve catalysts at some st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Reaction
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrolyse
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis is the cleavage of biomolecules where a water molecule is consumed to effect the separation of a larger molecule into component parts. When a carbohydrate is broken into its component sugar molecules by hydrolysis (e.g., sucrose being broken down into glucose and fructose), this is recognized as saccharification. Hydrolysis reactions can be the reverse of a condensation reaction in which two molecules join into a larger one and eject a water molecule. Thus hydrolysis adds water to break down, whereas condensation builds up by removing water. Types Usually hydrolysis is a chemical process in which a molecule of water is added to a substance. Sometimes this addition causes both the substance and water molecule to split into two parts. In su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C-terminus
The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is translated from messenger RNA, it is created from N-terminus to C-terminus. The convention for writing peptide sequences is to put the C-terminal end on the right and write the sequence from N- to C-terminus. Chemistry Each amino acid has a carboxyl group and an amine group. Amino acids link to one another to form a chain by a dehydration reaction which joins the amine group of one amino acid to the carboxyl group of the next. Thus polypeptide chains have an end with an unbound carboxyl group, the C-terminus, and an end with an unbound amine group, the N-terminus. Proteins are naturally synthesized starting from the N-terminus and ending at the C-terminus. Function C-terminal retention signals While the N-terminus of a protein often co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potyviridae
''Potyviridae'' is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. The family has 12 genera and 235 species, three of which are unassigned to a genus. Structure Potyvirid virions are nonenveloped, flexuous filamentous, rod-shaped particles. The diameter is around 12–15 nm, with a length of 200–300 nm. Genome Genomes are linear and usually nonsegmented, around 8–12kb in length, consisting of positive-sense RNA, which is surrounded by a protein coat made up of a single viral encoded protein called a capsid. All induce the formation of virus inclusion bodies called cylindrical inclusions (‘pinwheels’) in their hosts. These consist of a single protein (about 70 kDa) made in their hosts from a single viral genome product. Member viruses encode large polypeptides that are cleaved into mature proteins. In 5'–3' order these proteins are * P1 (a serine prot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potyvirus
''Potyvirus'' is a genus of positive-strand RNA viruses in the family ''Potyviridae''. Plants serve as natural hosts. The genus is named after member virus ''potato virus Y''. Potyviruses account for about thirty percent of the currently known plant viruses. Like begomoviruses, members of this genus may cause significant losses in agricultural, pastoral, horticultural, and ornamental crops. More than 200 species of aphids spread potyviruses, and most are from the subfamily ''Aphidinae'' (genera ''Macrosiphum'' and ''Myzus''). The genus contains 190 species. Virology Structure The virion is non-enveloped with a flexuous and filamentous nucleocapsid, 680 to 900 nanometers (nm) long and is 11–20 nm in diameter. The nucleocapsid contains around 2000 copies of the capsid protein. The symmetry of the nucleocapsid is helical with a pitch of 3.4 nm. Genome The genome is a linear, positive-sense, single-stranded RNA ranging in size from 9,000–12,000 nucleotide bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ipomovirus
''Ipomovirus'' is a genus of positive-strand RNA viruses in the family '' Potyviridae''. Member viruses infect plants and are transmitted by whiteflies ('' Bemisia tabaci''). The name of the genus is derived from '' Ipomoea'' – the generic name of sweet potato. There are seven species in this genus. Structure Viruses in genus ''Ipomovirus'' are non-enveloped, with flexuous and filamentous geometries. The diameter is around 12–15 nm, and may have a variety of lengths depending on the species (for single segmented species lengths of around 650–900 nm, or for double segmented species 200–300 nm and 500–600 nm). The capsid has helical symmetry with a pitch of 3.4 nm. They induce characteristic inclusion bodies (pinwheels) within infected plant cells. Genome The genome is either monpartite or bipartite depending on the species. Member viruses have linear, single stranded RNA genome of positive polarity about 10-11 kilobases in length. The 3’ terminus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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