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Synthase
In biochemistry, a synthase is an enzyme that catalyses a synthesis process. Note that, originally, biochemical nomenclature distinguished synthetases and synthases. Under the original definition, synthases do not use energy from nucleoside triphosphates (such as ATP, GTP, CTP, TTP, and UTP), whereas synthetases do use nucleoside triphosphates. However, the Joint Commission on Biochemical Nomenclature (JCBN) dictates that 'synthase' can be used with any enzyme that catalyzes synthesis (whether or not it uses nucleoside triphosphates), whereas 'synthetase' is to be used synonymously with 'ligase'. Examples * ATP synthase * Citrate synthase * Tryptophan synthase * Pseudouridine synthase * Fatty acid synthase * Cellulose synthase (UDP-forming) * Cellulose synthase (GDP-forming) In enzymology, a cellulose synthase (GDP-forming) () is an enzyme that catalyzes the chemical reaction :GDP-glucose + (1,4-beta-D-glucosyl)n \rightleftharpoons GDP + (1,4-beta-D-glucosyl)n+1 Thus, the tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATP Synthase
ATP synthase is a protein that catalyzes the formation of the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (Pi). It is classified under ligases as it changes ADP by the formation of P-O bond (phosphodiester bond). ATP synthase is a molecular machine. The overall reaction catalyzed by ATP synthase is: * ADP + Pi + 2H+out ATP + H2O + 2H+in The formation of ATP from ADP and Pi is energetically unfavorable and would normally proceed in the reverse direction. In order to drive this reaction forward, ATP synthase couples ATP synthesis during cellular respiration to an electrochemical gradient created by the difference in proton (H+) concentration across the inner mitochondrial membrane in eukaryotes or the plasma membrane in bacteria. During photosynthesis in plants, ATP is synthesized by ATP synthase using a proton gradient created in the thylakoid lumen through the thylakoid membrane and into the chloroplast stro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fatty Acid Synthase
Fatty acid synthase (FAS) is an enzyme that in humans is encoded by the ''FASN'' gene. Fatty acid synthase is a multi-enzyme protein that catalyzes fatty acid synthesis. It is not a single enzyme but a whole enzymatic system composed of two identical 272 kDa multifunctional polypeptides, in which substrates are handed from one functional domain to the next. Its main function is to catalyze the synthesis of palmitate (C16:0, a long-chain saturated fatty acid) from acetyl-CoA and malonyl-CoA, in the presence of NADPH. The fatty acids are synthesized by a series of decarboxylative Claisen condensation reactions from acetyl-CoA and malonyl-CoA. Following each round of elongation the beta keto group is reduced to the fully saturated carbon chain by the sequential action of a ketoreductase (KR), dehydratase (DH), and enoyl reductase (ER). The growing fatty acid chain is carried between these active sites while attached covalently to the phosphopantetheine prosthetic group of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cellulose Synthase (UDP-forming)
The UDP-forming form of cellulose synthase () is the main enzyme that produces cellulose. Systematically, it is known as ''UDP-glucose:(1→4)-β-D-glucan 4-β-D-glucosyltransferase'' in enzymology. It catalyzes the chemical reaction: : UDP-glucose + 1→4)-β-D-glucosylsub>n = UDP + 1→4)-β-D-glucosylsub>n+1 A similar enzyme utilizes GDP-glucose, cellulose synthase (GDP-forming) ( EC 2.4.1.29). This family of enzymes is found in bacteria and plants alike. Plant members are usually known as ''CesA'' (cellulose synthase) or the tentative ''CslA'' (cellulose synthase-like), while bacterial members may additionally be known as ''BcsA'' (bacterial cellulose synthase) or ''CelA'' (simply "cellulose"). Plants acquired ''CesA'' from the endosymbiosis event that produced the chloroplast. This family belongs to glucosyltransferase family 2 (GT2). Glycosyltransferases are involved in the biosynthesis and hydrolysis of the bulk of earth's biomass. There are known to be about seve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tryptophan Synthase
Tryptophan synthase or tryptophan synthetase is an enzyme () that catalyses the final two steps in the biosynthesis of tryptophan. It is commonly found in Eubacteria, Archaebacteria, Protista, Fungi, and Plantae. However, it is absent from Animalia. It is typically found as an α2β2 tetramer. The α subunits catalyze the reversible formation of indole and glyceraldehyde-3-phosphate (G3P) from indole-3-glycerol phosphate (IGP). The β subunits catalyze the irreversible condensation of indole and serine to form tryptophan in a pyridoxal phosphate (PLP) dependent reaction. Each α active site is connected to a β active site by a 25 angstrom long hydrophobic channel contained within the enzyme. This facilitates the diffusion of indole formed at α active sites directly to β active sites in a process known as substrate channeling. The active sites of tryptophan synthase are allosterically coupled. Enzyme structure Subunits: Tryptophan synthase typically exists as an α-ββ-α comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biosynthesis
Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds, or joined to form macromolecules. This process often consists of metabolic pathways. Some of these biosynthetic pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these biosynthetic pathways include the production of lipid membrane components and nucleotides. Biosynthesis is usually synonymous with anabolism. The prerequisite elements for biosynthesis include: precursor compounds, chemical energy (e.g. ATP), and catalytic enzymes which may require coenzymes (e.g.NADH, NADPH). These elements create monomers, the building blocks for macromolecules. Some important biological macromolecules include: proteins, which are composed of amino acid monomers joined via peptide bon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citrate Synthase
The enzyme citrate synthase E.C. 2.3.3.1 (previously 4.1.3.7)] exists in nearly all living cells and stands as a pace-making enzyme in the first step of the citric acid cycle (or Krebs cycle). Citrate synthase is localized within eukaryotic cells in the mitochondrial matrix, but is encoded by nuclear DNA rather than mitochondrial. It is synthesized using cytoplasmic ribosomes, then transported into the mitochondrial matrix. Citrate synthase is commonly used as a quantitative enzyme marker for the presence of intact mitochondria. Maximal activity of citrate synthase indicates the mitochondrial content of skeletal muscle. The maximal activity can be increased by endurance training or high-intensity interval training, but maximal activity is further increased with high-intensity interval training. Citrate synthase catalyzes the condensation reaction of the two-carbon acetate residue from acetyl coenzyme A and a molecule of four-carbon oxaloacetate to form the six-carbon citrate: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudouridine
Pseudouridine (abbreviated by the Greek letter psi- Ψ) is an isomer of the nucleoside uridine in which the uracil is attached via a carbon-carbon instead of a nitrogen-carbon glycosidic bond. (In this configuration, uracil is sometimes referred to as 'pseudouracil'.) Pseudouridine is the most abundant RNA modification in cellular RNA. After transcription and following synthesis, RNA can be modified with over 100 chemically distinct modifications. These can potentially regulate RNA expression post-transcriptionally, in addition to the four standard nucleotides and play a variety of roles in the cell including translation, localization and stabilization of RNA. Pseudouridine, being one of them, is the C5-glycoside isomer of uridine that contains a C-C bond between C1 of the ribose sugar and C5 of uracil, rather than usual C1-N1 bond found in uridine. The C-C bond gives it more rotational freedom and conformational flexibility. In addition, pseudouridine has an extra hydrogen bond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthetase
In biochemistry, a ligase is an enzyme that can catalyze the joining (Ligation (molecular biology), 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 laboratory, laboratories to join together DNA fragments. Other common names for ligases include the word "synth ... [...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] |
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 reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cellulose Synthase (GDP-forming)
In enzymology, a cellulose synthase (GDP-forming) () is an enzyme that catalyzes the chemical reaction :GDP-glucose + (1,4-beta-D-glucosyl)n \rightleftharpoons GDP + (1,4-beta-D-glucosyl)n+1 Thus, the two substrates of this enzyme are GDP-glucose and (1,4-beta-D-glucosyl)n, whereas its two products are GDP and (1,4-beta-D-glucosyl)n+1. This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is GDP-glucose:1,4-beta-D-glucan 4-beta-D-glucosyltransferase. Other names in common use include cellulose synthase (guanosine diphosphate-forming), cellulose synthetase, guanosine diphosphoglucose-1,4-beta-glucan glucosyltransferase, and guanosine diphosphoglucose-cellulose glucosyltransferase. This enzyme participates in starch and sucrose metabolism. , no proteins with this activity are known in the UniProt/NiceZYme or the gene ontology The Gene Ontology (GO) is a major bioinformatics initiative to u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biochemistry
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Voet (2005), p. 3. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells,Karp (2009), p. 2. in turn relating greatly to the understanding of tissues and organs, as well as organism structure and function.Miller (2012). p. 62. Biochemistry is closely related to molecular biology, which is the study of the molecular mechanisms of biological phenomena.As ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
