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Glutamate Racemase
In enzymology, glutamate racemase (MurI with a capital ''i'') () is an enzyme that catalysis, catalyzes the chemical reaction :L-glutamate \rightleftharpoons D-glutamate Hence, this enzyme RacE has one substrate (biochemistry), substrate, glutamic acid, L-glutamate, and one product (chemistry), product, D-glutamate. This enzyme belongs to the family of isomerases, specifically those racemases and epimerases acting on amino acids and derivatives, including proline racemase, aspartate racemase, and diaminopimelate epimerase. This enzyme participates in Glutamic acid#Metabolism, glutamate metabolism that is essential for cell wall biosynthesis in bacteria. Glutamate racemase performs the additional function of gyrase inhibition, preventing gyrase from binding to DNA. Glutamate racemase (MurI) serves two distinct metabolic functions: primarily, it is a critical enzyme in cell wall biosynthesis, but also plays a role in gyrase inhibition. The ability of glutamate racemase and other p ... [...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] |
N-terminus
The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the amine group is bonded to the carboxylic group of another amino acid, making it a chain. That leaves a free carboxylic group at one end of the peptide, called the C-terminus, and a free amine group on the other end called the N-terminus. By convention, peptide sequences are written N-terminus to C-terminus, left to right (in LTR writing systems). This correlates the translation direction to the text direction, because when a protein is translated from messenger RNA, it is created from the N-terminus to the C-terminus, as amino acids are added to the carboxyl end of the protein. Chemistry Each amino acid has an amine group and a carboxylic group. Amino acids link to one another by peptide bonds which form through a dehydration reaction that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2OHV
An overhead valve (OHV) engine, sometimes called a ''pushrod engine'', is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with earlier flathead engines, where the valves were located below the combustion chamber in the engine block. Although an overhead camshaft (OHC) engine also has overhead valves, the common usage of the term "overhead valve engine" is limited to engines where the camshaft is located in the engine block. In these traditional OHV engines, the motion of the camshaft is transferred using pushrods (hence the term "pushrod engine") and rocker arms to operate the valves at the top of the engine. Some early intake-over-exhaust engines used a hybrid design combining elements of both side-valves and overhead valves. History Predecessors The first internal combustion engines were based on steam engines and therefore used slide valves. This was the case for the first Otto engine, which was first succes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peptidoglycan
Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall (murein sacculus) characteristic of most bacteria (domain ''Bacteria''). The sugar component consists of alternating residues of β-(1,4) linked ''N''-acetylglucosamine (NAG) and ''N''-acetylmuramic acid (NAM). Attached to the ''N''-acetylmuramic acid is a oligopeptide chain made of three to five amino acids. The peptide chain can be cross-linked to the peptide chain of another strand forming the 3D mesh-like layer. Peptidoglycan serves a structural role in the bacterial cell wall, giving structural strength, as well as counteracting the osmotic pressure of the cytoplasm. This repetitive linking results in a dense peptidoglycan layer which is critical for maintaining cell form and withstanding high osmotic pressures, and it is regularly replaced by peptidoglycan production. Pep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Racemization
In chemistry, racemization is a conversion, by heat or by chemical reaction, of an optically active compound into a racemic (optically inactive) form. This creates a 1:1 molar ratio of enantiomers and is referred too as a racemic mixture (i.e. contain equal amount of (+) and (−) forms). Plus and minus forms are called Dextrorotation and levorotation. The D and L enantiomers are present in equal quantities, the resulting sample is described as a racemic mixture or a racemate. Racemization can proceed through a number of different mechanisms, and it has particular significance in pharmacology as different enantiomers may have different pharmaceutical effects. Stereochemistry Chiral molecules have two forms (at each point of asymmetry), which differ in their optical characteristics: The ''levorotatory form'' (the ''(−)-form'') will rotate counter-clockwise on the plane of polarization of a beam of light, whereas the ''dextrorotatory'' form (the ''(+)-form'') will rotate clockw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Side Chain
In organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called the "main chain" or backbone. The side chain is a hydrocarbon branching element of a molecule that is attached to a larger hydrocarbon backbone. It is one factor in determining a molecule's properties and reactivity. A side chain is also known as a pendant chain, but a pendant group (side group) has a different definition. Conventions The placeholder R is often used as a generic placeholder for alkyl (saturated hydrocarbon) group side chains in chemical structure diagrams. To indicate other non-carbon groups in structure diagrams, X, Y, or Z are often used. History The ''R'' symbol was introduced by 19th-century French chemist Charles Frédéric Gerhardt, who advocated its adoption on the grounds that it would be widely recognizable and intelligible given its correspondence in multiple European languages to the initial letter of "root" or "residue": ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peptide Bond
In organic chemistry, a peptide bond is an amide type of covalent chemical bond linking two consecutive alpha-amino acids from C1 (carbon number one) of one alpha-amino acid and N2 (nitrogen number two) of another, along a peptide or protein chain. It can also be called a eupeptide bond to distinguish it from an isopeptide bond, which is another type of amide bond between two amino acids. Synthesis When two amino acids form a ''dipeptide'' through a ''peptide bond'', it is a type of condensation reaction. In this kind of condensation, two amino acids approach each other, with the non-side chain (C1) carboxylic acid moiety of one coming near the non-side chain (N2) amino moiety of the other. One loses a hydrogen and oxygen from its carboxyl group (COOH) and the other loses a hydrogen from its amino group (NH2). This reaction produces a molecule of water (H2O) and two amino acids joined by a peptide bond (−CO−NH−). The two joined amino acids are called a dipeptide. The am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many are prepared from that acid. Spelling "Sulfate" is the spelling recommended by IUPAC, but "sulphate" was traditionally used in British English. Structure The sulfate anion consists of a central sulfur atom surrounded by four equivalent oxygen atoms in a tetrahedral arrangement. The symmetry is the same as that of methane. The sulfur atom is in the +6 oxidation state while the four oxygen atoms are each in the −2 state. The sulfate ion carries an overall charge of −2 and it is the conjugate base of the bisulfate (or hydrogensulfate) ion, , which is in turn the conjugate base of , sulfuric acid. Organic sulfate esters, such as dimethyl sulfate, are covalent compounds and esters of sulfuric acid. The tetrahedral molecular geometry of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cysteine
Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. When present as a deprotonated catalytic residue, sometimes the symbol Cyz is used. The deprotonated form can generally be described by the symbol Cym as well. The thiol is susceptible to oxidation to give the disulfide derivative cystine, which serves an important structural role in many proteins. In this case, the symbol Cyx is sometimes used. When used as a food additive, it has the E number E920. Cysteine is encoded by the codons UGU and UGC. The sulfur-containing amino acids cysteine and methionine are more easily oxidized than the other amino acids. Structure Like other amino acids (not as a residue of a protein), cysteine exists as a zwitterion. Cysteine has chirality in the older / notation based on homology to - and -glyceraldehyde. In the newer ''R''/''S'' system of designating chi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Dimer
In biochemistry, a protein dimer is a macromolecular complex formed by two protein monomers, or single proteins, which are usually non-covalently bound. Many macromolecules, such as proteins or nucleic acids, form dimers. The word ''dimer'' has roots meaning "two parts", '' di-'' + '' -mer''. A protein dimer is a type of protein quaternary structure. A protein homodimer is formed by two identical proteins. A protein heterodimer is formed by two different proteins. Most protein dimers in biochemistry are not connected by covalent bonds. An example of a non-covalent heterodimer is the enzyme reverse transcriptase, which is composed of two different amino acid chains. An exception is dimers that are linked by disulfide bridges such as the homodimeric protein NEMO. Some proteins contain specialized domains to ensure dimerization (dimerization domains) and specificity. The G protein-coupled cannabinoid receptors have the ability to form both homo- and heterodimers with several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacillus Subtilis
''Bacillus subtilis'', known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges. As a member of the genus ''Bacillus'', ''B. subtilis'' is rod-shaped, and can form a tough, protective endospore, allowing it to tolerate extreme environmental conditions. ''B. subtilis'' has historically been classified as an obligate aerobe, though evidence exists that it is a facultative anaerobe. ''B. subtilis'' is considered the best studied Gram-positive bacterium and a model organism to study bacterial chromosome replication and cell differentiation. It is one of the bacterial champions in secreted enzyme production and used on an industrial scale by biotechnology companies. Description ''Bacillus subtilis'' is a Gram-positive bacterium, rod-shaped and catalase-positive. It was originally named ''Vibrio subtilis'' by Christian Gottfried Ehrenberg, and renamed ''B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
