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Enzyme Promiscuity
Enzyme promiscuity is the ability of an enzyme to catalyse a fortuitous side reaction in addition to its main reaction. Although enzymes are remarkably specific catalysts, they can often perform side reactions in addition to their main, native catalytic activity. These promiscuous activities are usually slow relative to the main activity and are under neutral selection. Despite ordinarily being physiologically irrelevant, under new selective pressures these activities may confer a fitness benefit therefore prompting the evolution of the formerly promiscuous activity to become the new main activity. An example of this is the atrazine chlorohydrolase (''atzA'' encoded) from '' Pseudomonas sp.'' ADP that evolved from melamine deaminase (''triA'' encoded), which has very small promiscuous activity toward atrazine, a man-made chemical. Introduction Enzymes are evolved to catalyse a particular reaction on a particular substrate with a high catalytic efficiency (''kcat/KM'', ''cf''. Michae ... [...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] |
Last Universal Common Ancestor
The last universal common ancestor (LUCA) is the most recent population from which all organisms now living on Earth share common descent—the most recent common ancestor of all current life on Earth. This includes all cellular organisms; the origins of viruses are unclear but they share the same genetic code. LUCA probably harboured a variety of viruses. The LUCA is not the first life on Earth, but rather the latest form ancestral to all existing life. While there is no specific fossil evidence of the LUCA, the detailed biochemical similarity of all current life confirms its existence. Its characteristics can be inferred from shared features of modern genomes. These genes describe a complex life form with many co-adapted features, including transcription and translation mechanisms to convert information from DNA to RNA to proteins. The LUCA probably lived in the high-temperature water of deep sea vents near ocean-floor magma flows around 4 billion years ago. Histori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transaminase
Transaminases or aminotransferases are enzymes that catalyze a transamination reaction between an amino acid and an α- keto acid. They are important in the synthesis of amino acids, which form proteins. Function and mechanism An amino acid contains an amine (NH2) group. A keto acid contains a keto (=O) group. In transamination, the NH2 group on one molecule is exchanged with the =O group on the other molecule. The amino acid becomes a keto acid, and the keto acid becomes an amino acid. Most transaminases are protein enzymes. However, some transamination activities of the ribosome have been found to be catalyzed by ribozymes (RNA enzymes). Examples being the hammerhead ribozyme, the VS ribozyme and the hairpin ribozyme. Transaminases require the coenzyme pyridoxal phosphate, which is converted into pyridoxamine in the first half-reaction, when an amino acid is converted into a keto acid. Enzyme-bound pyridoxamine in turn reacts with pyruvate, oxaloacetate, or alpha- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rational Design
In chemical biology and biomolecular engineering, rational design (RD) is an umbrella term which invites the strategy of creating new molecules with a certain functionality, based upon the ability to predict how the molecule's structure (specifically derived from motifs) will affect its behavior through physical models. This can be done either from scratch or by making calculated variations on a known structure, and usually complements directed evolution. Applications As an example, rational design is used to decipher collagen stability, mapping ligand-receptor interactions, unveiling protein folding and dynamics, and creating extra-biological structures by using fluorinated amino acids. To treat cancer, rational design is used for targeted therapies where proteins are engineered to modify the communication of cells with their environment. There is also the rational design of alfa-alkyl auxin molecules, which are auxin analogs capable of binding and blocking the formation of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biocatalysis
Biocatalysis refers to the use of living (biological) systems or their parts to speed up (catalyze) chemical reactions. In biocatalytic processes, natural catalysts, such as enzymes, perform chemical transformations on organic compounds. Both enzymes that have been more or less isolated and enzymes still residing inside living cells are employed for this task. Modern biotechnology, specifically directed evolution, has made the production of modified or non-natural enzymes possible. This has enabled the development of enzymes that can catalyze novel small molecule transformations that may be difficult or impossible using classical synthetic organic chemistry. Utilizing natural or modified enzymes to perform organic synthesis is termed chemoenzymatic synthesis; the reactions performed by the enzyme are classified as chemoenzymatic reactions. History Biocatalysis underpins some of the oldest chemical transformations known to humans, for brewing predates recorded history. The oldest r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Metabolites
Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the normal growth, development, or reproduction of the organism. Instead, they generally mediate ecological interactions, which may produce a selective advantage for the organism by increasing its survivability or fecundity. Specific secondary metabolites are often restricted to a narrow set of species within a phylogenetic group. Secondary metabolites often play an important role in plant defense against herbivory and other interspecies defenses. Humans use secondary metabolites as medicines, flavourings, pigments, and recreational drugs. The term secondary metabolite was first coined by Albrecht Kossel, a 1910 Nobel Prize laureate for medicine and physiology in 1910. 30 years later a Polish botanist Friedrich Czapek described secondary met ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delphinidin
Delphinidin (also delphinidine) is an anthocyanidin, a primary plant pigment, and also an antioxidant. Delphinidin gives blue hues to flowers in the genera ''Viola'' and ''Delphinium''. It also gives the blue-red color of the grape that produces Cabernet Sauvignon, and can be found in cranberries and Concord grapes as well as pomegranates, and bilberries. Delphinidin, like nearly all other anthocyanidins, is pH-sensitive, i.e. a natural pH indicator, and changes from blue in basic solution to red in acidic solution. Glycosides Several glycosides derived from delphinidin are known: * Myrtillin (delphinidin-3-''O''-glucoside) and tulipanin (delphinidin-3-''O''-rutinoside) can be found in blackcurrant pomace. * Violdelphin (delphinidin 3-rutinoside-7-''O''-(6-''O''-(4-(6-''O''-(4-hydroxybenzoyl)-β-D-glucosyl)oxybenzoyl)-β-D-glucoside) is responsible for the purplish-blue flower color of '' Aconitum chinense''. * Nasunin (delphinidin-3-(''p''-coumaroylrutinoside)-5-gluc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Activity
Star activity is the relaxation or alteration of the specificity of restriction enzyme mediated cleavage of DNA that can occur under reaction conditions that differ significantly from those optimal for the enzyme. The result is typically cleavage at non-canonical recognition sites, or sometimes complete loss of specificity. Differences which can lead to star include low ionic strength, high pH, and high (> 5% v/v) glycerol concentrations. The latter condition is of particular practical interest, since commercial restriction enzymes are usually supplied in a buffer containing a substantial amount of glycerol (50% v/v is typical), meaning insufficient dilution of the enzyme solution can cause star activity; this problem most often arises during double or multiple digests. Star activity can happen because of presence of Mg2+, as is seen in HindIII, for example. The term star activity was introduced by Mayer who characterized the modified activity in EcoRI ''Eco''RI (pronounced "e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-proteinogenic Amino Acids
In biochemistry, non-coded or non-proteinogenic amino acids are distinct from the 22 proteinogenic amino acids (21 in eukaryotesplus formylmethionine in eukaryotes with prokaryote organelles like mitochondria) which are naturally encoded in the genome of organisms for the assembly of proteins. However, over 140 non-proteinogenic amino acids occur naturally in proteins and thousands more may occur in nature or be synthesized in the laboratory. Chemically synthesized amino acids can be called unnatural amino acids. Unnatural amino acids can be synthetically prepared from their native analogs via modifications such as amine alkylation, side chain substitution, structural bond extension cyclization, and isosteric replacements within the amino acid backbone. Many non-proteinogenic amino acids are important: * intermediates in biosynthesis, * in post-translational formation of proteins, * in a physiological role (e.g. components of bacterial cell walls, neurotransmitters and toxins), * n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-ribosomal Peptide
Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be made by bacteria inside these organisms. While there exist a wide range of peptides that are not synthesized by ribosomes, the term ''nonribosomal peptide'' typically refers to a very specific set of these as discussed in this article. Nonribosomal peptides are synthesized by nonribosomal peptide synthetases, which, unlike the ribosomes, are independent of messenger RNA. Each nonribosomal peptide synthetase can synthesize only one type of peptide. Nonribosomal peptides often have cyclic and/or branched structures, can contain non-proteinogenic amino acids including D-amino acids, carry modifications like '' N''-methyl and ''N''-formyl groups, or are glycosylated, acylated, halogenated, or hydroxylated. Cyclization of amino acids against the peptide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrocidine
Tyrocidine is a mixture of cyclic decapeptides produced by the bacteria ''Bacillus brevis'' found in soil. It can be composed of 4 different amino acid sequences, giving tyrocidine A–D (See figure 1). Tyrocidine is the major constituent of tyrothricin, which also contains gramicidin.Pubchem: Tyrocidine and Tyrothricin. Tyrocidine was the first commercially available antibiotic, but has been found to be toxic toward human blood and reproductive cells. The function of tyrocidine within its host ''B. brevis'' is thought to be regulation of sporulation. Tyrocidines A, B, and C are cyclic decapeptides. The biosynthesis of tyrocidine involves three enzymes. Parts of its sequence are identical to gramicidin S. History In 1939, the American microbiologist René Dubos discovered the soil microbe ''Bacillus brevis''. He observed the ability of the microbe to decompose the capsule of pneumococcus bacterium, rendering it harmless. From the soil microbe ''B. brevis'', he isolated t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacillus Brevis
''Brevibacillus brevis'' (formerly known as ''Bacillus brevis'') is a Gram-positive, aerobic, motile, spore-forming, rod-shaped bacterium commonly found in soil, air, water, and decaying matter. It is rarely associated with infectious diseases. The antibiotics gramicidin and tyrocidine were first isolated from it.Abedon, Stephen. "Bacteria Binomials." 26 Apr 1998. Ohio State University. 17 Jun 2006 . ''Brevibacillus brevis'' is catalase positive, amylase negative, casein negative, gelatinase positive, and indole negative; most strains are citrate users. Some strains are capable of oxidizing carbon monoxide Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simpl ... aerobically. Optimal growth occurs at 35 °C to 55 °C. References Paenibacillaceae Bacteria described i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
