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Site-directed Spin Labeling
Site-directed spin labeling (SDSL) is a technique for investigating the structure and local dynamics of proteins using electron spin resonance. The theory of SDSL is based on the specific reaction of spin labels with amino acids. A spin label's built-in protein structure can be detected by EPR spectroscopy. SDSL is also a useful tool in examinations of the protein folding process. Spin labeling Site-directed spin labeling (SDSL) was pioneered in the laboratory of Dr. W.L. Hubbell. In SDSL, sites for attachment of spin labels are introduced into recombinantly expressed proteins by site-directed mutagenesis. Functional group In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...s contained within the spin label determine their specificity. At neutral pH, protein thiol groups speci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metabolic reactions, DNA replication, Cell signaling, responding to stimuli, providing Cytoskeleton, structure to cells and Fibrous protein, organisms, and Intracellular transport, transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the Nucleic acid sequence, nucleotide sequence of their genes, and which usually results in protein folding into a specific Protein structure, 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called pep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Spin Resonance
Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials that have unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR), but the spins excited are those of the electrons instead of the atomic nuclei. EPR spectroscopy is particularly useful for studying metal complexes and organic radicals. EPR was first observed in Kazan State University by Soviet physicist Yevgeny Zavoisky in 1944, and was developed independently at the same time by Brebis Bleaney at the University of Oxford. Theory Origin of an EPR signal Every electron has a magnetic moment and spin quantum number s = \tfrac , with magnetic components m_\mathrm = + \tfrac or m_\mathrm = - \tfrac . In the presence of an external magnetic field with strength B_\mathrm , the electron's magnetic moment aligns itself either antiparallel ( m_\mathrm = - \tfrac ) or parallel ( m_\mathrm = + \tfrac ) to the fie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spin Label
A spin label (SL) is an organic molecule which possesses an unpaired electron, usually on a nitrogen atom, and the ability to bind to another molecule. Spin labels are normally used as tools for probing proteins or biological membrane-local dynamics using electron paramagnetic resonance spectroscopy. The site-directed spin labeling (SDSL) technique allows one to monitor a specific region within a protein. In protein structure examinations, amino acid-specific SLs can be used. The goal of spin labeling is somewhat similar to that of isotopic substitution in NMR spectroscopy. There one replaces an atom lacking a nuclear spin (and so is NMR-silent) with an isotope having a spin (and so is NMR-active). This technique is useful for tracking the chemical environment around an atom when full substitution with an NMR-active isotope is not feasible. Recently, spin-labelling has also been used to probe chemical local environment in NMR itself, in a technique known as Paramagnetic Relaxa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 appear in the genetic code of life. Amino acids can be classified according to the locations of the core structural functional groups ( alpha- , beta- , gamma- amino acids, etc.); other categories relate to polarity, ionization, and side-chain group type ( aliphatic, acyclic, aromatic, polar, etc.). In the form of proteins, amino-acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life on Earth and its emergence. Amino acids are formally named by the IUPAC- IUBMB Joint Commi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Spin Resonance
Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials that have unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR), but the spins excited are those of the electrons instead of the atomic nuclei. EPR spectroscopy is particularly useful for studying metal complexes and organic radicals. EPR was first observed in Kazan State University by Soviet physicist Yevgeny Zavoisky in 1944, and was developed independently at the same time by Brebis Bleaney at the University of Oxford. Theory Origin of an EPR signal Every electron has a magnetic moment and spin quantum number s = \tfrac , with magnetic components m_\mathrm = + \tfrac or m_\mathrm = - \tfrac . In the presence of an external magnetic field with strength B_\mathrm , the electron's magnetic moment aligns itself either antiparallel ( m_\mathrm = - \tfrac ) or parallel ( m_\mathrm = + \tfrac ) to the fie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Folding
Protein folding is the physical process by which a protein, after Protein biosynthesis, synthesis by a ribosome as a linear chain of Amino acid, amino acids, changes from an unstable random coil into a more ordered protein tertiary structure, three-dimensional structure. This structure permits the protein to become biologically functional or active. The folding of many proteins begins even during the translation of the polypeptide chain. The amino acids interact with each other to produce a well-defined three-dimensional structure, known as the protein's native state. This structure is determined by the amino-acid sequence or primary structure. The correct three-dimensional structure is essential to function, although some parts of functional proteins Intrinsically unstructured proteins, may remain unfolded, indicating that protein dynamics are important. Failure to fold into a native structure generally produces inactive proteins, but in some instances, misfolded proteins have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epr Spectrum
EPR may refer to: Science and technology * EPR (nuclear reactor), European Pressurised-Water Reactor * EPR paradox (Einstein–Podolsky–Rosen paradox), in physics * Earth potential rise, in electrical engineering * East Pacific Rise, a mid-oceanic ridge * Electron paramagnetic resonance * Engine pressure ratio, of a jet engine * Ethylene propylene rubber * Yevpatoria RT-70 radio telescope (Evpatoria planetary radar) * Bernays–Schönfinkel class or effectively propositional, in mathematical logic * Endpoint references in Web addressing * Ethnic Power Relations, dataset of ethnic groups * ePrivacy Regulation (ePR), proposal for the regulation of various privacy-related topics, mostly in relation to electronic communications within the European Union Medicine * Enhanced permeability and retention effect, a controversial concept in cancer research * Emergency Preservation and Resuscitation, a medical procedure * Electronic patient record Environment * UNECE Environmental P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Site-directed Mutagenesis
Site-directed mutagenesis is a molecular biology method that is used to make specific and intentional mutating changes to the DNA sequence of a gene and any gene products. Also called site-specific mutagenesis or oligonucleotide-directed mutagenesis, it is used for investigating the structure and biological activity of DNA, RNA, and protein molecules, and for protein engineering. Site-directed mutagenesis is one of the most important laboratory techniques for creating DNA libraries by introducing mutations into DNA sequences. There are numerous methods for achieving site-directed mutagenesis, but with decreasing costs of oligonucleotide synthesis, artificial gene synthesis is now occasionally used as an alternative to site-directed mutagenesis. Since 2013, the development of the CRISPR/Cas9 technology, based on a prokaryotic viral defense system, has also allowed for the editing of the genome, and mutagenesis may be performed ''in vivo'' with relative ease. History Early atte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Functional Group
In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition. This enables systematic prediction of chemical reactions and behavior of chemical compounds and the design of chemical synthesis. The Reactivity (chemistry), reactivity of a functional group can be modified by other functional groups nearby. Functional group interconversion can be used in retrosynthetic analysis to plan organic synthesis. A functional group is a group of atoms in a molecule with distinctive Chemical property, chemical properties, regardless of the other atoms in the molecule. The atoms in a functional group are linked to each other and to the rest of the molecule by covalent bonds. For repeating units of polymers, functional groups attach to their Chemical polarity, nonp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cysteine
Cysteine (; symbol Cys or C) is a semiessential proteinogenic amino acid with the chemical formula, formula . The thiol side chain in cysteine enables the formation of Disulfide, disulfide bonds, and often participates in enzymatic reactions as a nucleophile. Cysteine is chiral, but both D and L-cysteine are found in nature. LCysteine is a protein monomer in all biota, and D-cysteine acts as a signaling molecule in mammalian nervous systems. Cysteine is named after its discovery in urine, which comes from the urinary bladder or cyst, from Ancient Greek, Greek κύστις ''kýstis'', "bladder". The thiol is susceptible to oxidation to give the disulfide bond, disulfide derivative cystine, which serves an important structural role in many proteins. In this case, the symbol Cyx is sometimes used. The deprotonated form can generally be described by the symbol Cym as well. When used as a food additive, cysteine has the E number E920. Cysteine is Genetic code, encoded by the codo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrrolidine
Pyrrolidine, also known as tetrahydropyrrole, is an organic compound with the molecular formula (CH2)4NH. It is a cyclic secondary amine, also classified as a saturated heterocycle. It is a colourless liquid that is miscible with water and most organic solvents. It has a characteristic odor that has been described as "ammoniacal, fishy, shellfish-like". In addition to pyrrolidine itself, many substituted pyrrolidines are known. Production and synthesis Industrial production Pyrrolidine is prepared industrially by the reaction of 1,4-butanediol and ammonia at a temperature of 165–200 °C and a pressure of 17–21 MPa in the presence of a cobalt- and nickel oxide catalyst, which is supported on alumina. : The reaction is carried out in the liquid phase in a continuous tube- or tube bundle reactor, which is operated in the cycle gas method. The catalyst is arranged as a fixed-bed and the conversion is carried out in the downflow mode. The product is obtained after m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
