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Allostery
In the fields of biochemistry and pharmacology an allosteric regulator (or allosteric modulator) is a substance that binds to a site on an enzyme or Receptor (biochemistry), receptor distinct from the active site, resulting in a conformational change that alters the protein's activity, either enhancing or inhibiting its function. In contrast, substances that bind directly to an enzyme's active site or the binding site of the endogenous ligand of a receptor are called orthosteric regulators or modulators. The site to which the effector binds is termed the ''allosteric site'' or ''regulatory site''. Allosteric sites allow effectors to bind to the protein, often resulting in a conformational change and/or a change in protein dynamics. Effectors that enhance the protein's activity are referred to as ''allosteric activators'', whereas those that decrease the protein's activity are called ''allosteric inhibitors''. Allosteric regulations are a natural example of control loops, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allosteric Regulation
In the fields of biochemistry and pharmacology an allosteric regulator (or allosteric modulator) is a substance that binds to a site on an enzyme or receptor distinct from the active site, resulting in a conformational change that alters the protein's activity, either enhancing or inhibiting its function. In contrast, substances that bind directly to an enzyme's active site or the binding site of the endogenous ligand of a receptor are called orthosteric regulators or modulators. The site to which the effector binds is termed the ''allosteric site'' or ''regulatory site''. Allosteric sites allow effectors to bind to the protein, often resulting in a conformational change and/or a change in protein dynamics. Effectors that enhance the protein's activity are referred to as ''allosteric activators'', whereas those that decrease the protein's activity are called ''allosteric inhibitors''. Allosteric regulations are a natural example of control loops, such as feedback from do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jean-Pierre Changeux
Jean-Pierre Changeux (; born 6 April 1936) is a French neuroscientist known for his research in several fields of biology, from the structure and function of proteins (with a focus on the allosteric proteins), to the early development of the nervous system up to cognitive functions. Although being famous in biological sciences for the MWC model, the identification and purification of the nicotinic acetylcholine receptor, the theory of epigenesis by synapse selection and the global neuronal workspace theory for conscious processing are also notable scientific achievements. Changeux is known by the non-scientific public for his ideas regarding the connection between mind and physical brain. As put forth in his book, ''Conversations on Mind, Matter and Mathematics'', Changeux strongly supports the view that the nervous system functions in a projective rather than reactive style and that interaction with the environment, rather than being instructive, results in the selection amongst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morpheein
Morpheeins are proteins that can form two or more different homo-oligomers (morpheein forms), but must come apart and change shape to convert between forms. The alternate shape may reassemble to a different oligomer. The shape of the subunit dictates which oligomer is formed. Each oligomer has a finite number of subunits (stoichiometry). Morpheeins can interconvert between forms under physiological conditions and can exist as an equilibrium of different oligomers. These oligomers are physiologically relevant and are not misfolded protein; this distinguishes morpheeins from prions and amyloid. The different oligomers have distinct functionality. Interconversion of morpheein forms can be a structural basis for allosteric regulation, an idea noted many years ago, and later revived. A mutation that shifts the normal equilibrium of morpheein forms can serve as the basis for a conformational disease. Features of morpheeins can be exploited for drug discovery. The dice image (Fig 1) r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porphobilinogen Synthase
Aminolevulinic acid dehydratase (porphobilinogen synthase, or ALA dehydratase, or aminolevulinate dehydratase) is an enzyme () that in humans is encoded by the ''ALAD'' gene. Porphobilinogen synthase (or ALA dehydratase, or aminolevulinate dehydratase) synthesizes porphobilinogen through the asymmetric condensation of two molecules of aminolevulinic acid. All natural tetrapyrroles, including hemes, chlorophylls and vitamin B12, share porphobilinogen as a common precursor. Porphobilinogen synthase is the prototype morpheein. Function It catalyzes the following reaction, the second step of the biosynthesis of porphyrin: :2 5- Aminolevulinic acid \rightleftharpoons porphobilinogen + 2 H2O It therefore catalyzes the condensation of 2 molecules of 5-aminolevulinate to form porphobilinogen (a precursor of heme, cytochromes and other hemoproteins). This reaction is the first common step in the biosynthesis of all biological tetrapyrroles. Zinc is essential for enzymatic activity. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endogenous Ligand
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. The etymology stems from Latin ''ligare'', which means 'to bind'. In protein-ligand binding, the ligand is usually a molecule which produces a signal by binding to a site on a target protein. The binding typically results in a change of conformational isomerism (conformation) of the target protein. In DNA-ligand binding studies, the ligand can be a small molecule, ion, or protein which binds to the DNA double helix. The relationship between ligand and binding partner is a function of charge, hydrophobicity, and molecular structure. Binding occurs by intermolecular forces, such as ionic bonds, hydrogen bonds and Van der Waals forces. The association or docking is actually reversible through dissociation. Measurably irreversible covalent bonding between a ligand and target molecule is atypical in biological systems. In contrast to the definition of l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand (biochemistry)
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. The etymology stems from Latin ''ligare'', which means 'to bind'. In protein-ligand binding, the ligand is usually a molecule which produces a signal by binding to a site on a target protein. The binding typically results in a change of conformational isomerism (conformation) of the target protein. In DNA-ligand binding studies, the ligand can be a small molecule, ion, or protein which binds to the DNA double helix. The relationship between ligand and binding partner is a function of charge, hydrophobicity, and molecular structure. Binding occurs by intermolecular forces, such as ionic bonds, hydrogen bonds and Van der Waals forces. The association or docking is actually reversible through dissociation. Measurably irreversible covalent bonding between a ligand and target molecule is atypical in biological systems. In contrast to the definition o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Subunit
In structural biology, a protein subunit is a polypeptide chain or single protein molecule that assembles (or "''coassembles''") with others to form a protein complex. Large assemblies of proteins such as viruses often use a small number of types of protein subunits as building blocks. A subunit is often named with a Greek or Roman letter, and the numbers of this type of subunit in a protein is indicated by a subscript. For example, ATP synthase has a type of subunit called α. Three of these are present in the ATP synthase molecule, leading to the designation α3. Larger groups of subunits can also be specified, like α3β3-hexamer and c-ring. Naturally occurring proteins that have a relatively small number of subunits are referred to as oligomeric.Quote: ''Oligomer molecule: A molecule of intermediate relative molecular mass, the structure of which essentially comprises a small plurality of units derived, actually or conceptually, from molecules of lower relative molecula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sequential Model
The sequential model (also known as the KNF model) is a theory that describes cooperativity of protein subunits. Koshland, D.E., Némethy, G. and Filmer, D. (1966) Comparison of experimental binding data and theoretical models in proteins containing subunits. Biochemistry 5, 365–385DOI: 10.1021/bi00865a047/ref> It postulates that a protein's conformation changes with each binding of a ligand, thus sequentially changing its affinity for the ligand at neighboring binding sites. It gives one explanation for cooperative binding. Overview This model for allosteric regulation of enzymes suggests that the subunits of multimeric proteins have two conformational states. The binding of the ligand causes conformational change in the other subunits of the multimeric protein. Although the subunits go through conformational changes independently (as opposed to in the MWC model), the switch of one subunit makes the other subunits more likely to change, by reducing the energy needed for subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme Model
An enzyme () is a protein that acts as a biological catalyst 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 include catalytic RNA molecules, also called ribozymes. They are sometimes described as a ''type'' of enzyme rather than being ''like'' an enzyme, but even in the decades ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jeffries Wyman (biologist)
Jeffries Wyman (June 21, 1901 – November 4, 1995) was an American molecular biologist and biophysicist notable for his research of proteins, amino acids, and on the physical chemistry of hemoglobin, Obituary, ''The New York Times'' (9 November 1995)... including the classic Monod–Wyman–Changeux model. Life Wyman was born in West Newton, Massachusetts, in 1901. He graduated ''summa cum laude'' from Harvard College in 1923 with a degree in philosophy and biology. He then received a Ph.D. from University College London. He was a professor of biology at Harvard University (1928–1951), director of a regional science office in the Middle East for Unesco (1955–1958), and a scientist at the Regina Elena and the Biochemistry Institute of the Sapienza University of Rome (1958–1984) before retiring. He died in Paris, France, in 1995. Wyman was a member of the National Academy of Sciences and of the American Academy of Arts and Sciences, the first scientific advisor to the US ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Energy Functional
Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and light. Energy is a Conservation law, conserved quantity—the law of conservation of energy states that energy can be Energy transformation, converted in form, but not created or destroyed. The unit of measurement for energy in the International System of Units (SI) is the joule (J). Forms of energy include the kinetic energy of a moving object, the potential energy stored by an object (for instance due to its position in a Classical field theory, field), the elastic energy stored in a solid object, chemical energy associated with chemical reactions, the radiant energy carried by electromagnetic radiation, the internal energy contained within a thermodynamic system, and rest energy associated with an object's rest mass. These are not mutual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
