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Anfinsen's Dogma
Anfinsen's dogma, also known as the thermodynamic hypothesis, is a postulate in molecular biology. It states that, at least for a small globular protein in its standard physiological environment, the native structure is determined only by the protein's amino acid sequence. The dogma was championed by the Nobel Prize Laureate Christian B. Anfinsen from his research on the folding of ribonuclease A. The postulate amounts to saying that, at the environmental conditions (temperature, solvent concentration and composition, etc.) at which folding occurs, the native structure is a unique, stable and kinetically accessible minimum of the free energy. In other words, there are three conditions for formation of a unique protein structure: *Uniqueness – Requires that the sequence does not have any other configuration with a comparable free energy. Hence the free energy minimum must be ''unchallenged''. *Stability – Small changes in the surrounding environment cannot give rise to changes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chaperone (protein)
In molecular biology, molecular chaperones are proteins that assist the conformational folding or unfolding of large proteins or macromolecular protein complexes. There are a number of classes of molecular chaperones, all of which function to assist large proteins in proper protein folding during or after synthesis, and after partial denaturation. Chaperones are also involved in the translocation of proteins for proteolysis. The first molecular chaperones discovered were a type of assembly chaperones which assist in the assembly of nucleosomes from folded histones and DNA. One major function of molecular chaperones is to prevent the aggregation of misfolded proteins, thus many chaperone proteins are classified as heat shock proteins, as the tendency for protein aggregation is increased by heat stress. The majority of molecular chaperones do not convey any steric information for protein folding, and instead assist in protein folding by binding to and stabilizing folding interme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Local Minimum
In mathematical analysis, the maxima and minima (the respective plurals of maximum and minimum) of a function, known collectively as extrema (the plural of extremum), are the largest and smallest value of the function, either within a given range (the ''local'' or ''relative'' extrema), or on the entire domain (the ''global'' or ''absolute'' extrema). Pierre de Fermat was one of the first mathematicians to propose a general technique, adequality, for finding the maxima and minima of functions. As defined in set theory, the maximum and minimum of a set are the greatest and least elements in the set, respectively. Unbounded infinite sets, such as the set of real numbers, have no minimum or maximum. Definition A real-valued function ''f'' defined on a domain ''X'' has a global (or absolute) maximum point at ''x''∗, if for all ''x'' in ''X''. Similarly, the function has a global (or absolute) minimum point at ''x''∗, if for all ''x'' in ''X''. The value of the function at a m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Kinetics
Chemical kinetics, also known as reaction kinetics, is the branch of physical chemistry that is concerned with understanding the rates of chemical reactions. It is to be contrasted with chemical thermodynamics, which deals with the direction in which a reaction occurs but in itself tells nothing about its rate. Chemical kinetics includes investigations of how experimental conditions influence the speed of a chemical reaction and yield information about the reaction's mechanism and transition states, as well as the construction of mathematical models that also can describe the characteristics of a chemical reaction. History In 1864, Peter Waage and Cato Guldberg pioneered the development of chemical kinetics by formulating the law of mass action, which states that the speed of a chemical reaction is proportional to the quantity of the reacting substances.C.M. Guldberg and P. Waage,"Studies Concerning Affinity" ''Forhandlinger i Videnskabs-Selskabet i Christiania'' (1864), 35P. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gibbs Free Energy
In thermodynamics, the Gibbs free energy (or Gibbs energy; symbol G) is a thermodynamic potential that can be used to calculate the maximum amount of work that may be performed by a thermodynamically closed system at constant temperature and pressure. It also provides a necessary condition for processes such as chemical reactions that may occur under these conditions. The Gibbs free energy change , measured in joules in SI) is the ''maximum'' amount of non-expansion work that can be extracted from a closed system (one that can exchange heat and work with its surroundings, but not matter) at fixed temperature and pressure. This maximum can be attained only in a completely reversible process. When a system transforms reversibly from an initial state to a final state under these conditions, the decrease in Gibbs free energy equals the work done by the system to its surroundings, minus the work of the pressure forces. The Gibbs energy is the thermodynamic potential that is minim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Potential
Membrane potential (also transmembrane potential or membrane voltage) is the difference in electric potential between the interior and the exterior of a biological cell. That is, there is a difference in the energy required for electric charges to move from the internal to exterior cellular environments and vice versa, as long as there is no acquisition of kinetic energy or the production of radiation. The concentration gradients of the charges directly determine this energy requirement. For the exterior of the cell, typical values of membrane potential, normally given in units of milli volts and denoted as mV, range from –80 mV to –40 mV. All animal cells are surrounded by a membrane composed of a lipid bilayer with proteins embedded in it. The membrane serves as both an insulator and a diffusion barrier to the movement of ions. Transmembrane proteins, also known as ion transporter or ion pump proteins, actively push ions across the membrane and establish concentration gradi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Phosphorylation
Protein phosphorylation is a reversible post-translational modification of proteins in which an amino acid residue is phosphorylated by a protein kinase by the addition of a covalently bound phosphate group. Phosphorylation alters the structural conformation of a protein, causing it to become either activated or deactivated, or otherwise modifying its function. Approximately 13000 human proteins have sites that are phosphorylated. The reverse reaction of phosphorylation is called dephosphorylation, and is catalyzed by protein phosphatases. Protein kinases and phosphatases work independently and in a balance to regulate the function of proteins. The amino acids most commonly phosphorylated are serine, threonine, tyrosine in eukaryotes, and also histidine in prokaryotes and plants (though it is now known to be common in humans). These phosphorylations play important and well-characterized roles in signaling pathways and metabolism. However, other amino acids can also be phosphory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KaiB (born 1997), Swedish footballer
{{Disambiguation, callsign ...
Kaib, KaiB, or KAIB may refer to: * KAIB (FM), one of the radio stations of Air 1 * KaiB, a gene * KAI Bandara, an Indonesian railway operator * Korea Aviation Accident Investigation Board * Rami Kaib Rami Kaib (; born 8 May 1997) is a Tunisian professional footballer who plays as a left-back for Eredivisie club SC Heerenveen. Kaib was born in Sweden and has Tunisian heritage; he represented his native country internationally at under-19 le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Dynamics
Proteins are generally thought to adopt unique structures determined by their amino acid sequences. However, proteins are not strictly static objects, but rather populate ensembles of (sometimes similar) conformations. Transitions between these states occur on a variety of length scales (tenths of Å to nm) and time scales (ns to s), and have been linked to functionally relevant phenomena such as allosteric signaling and enzyme catalysis. The study of protein dynamics is most directly concerned with the transitions between these states, but can also involve the nature and equilibrium populations of the states themselves. These two perspectives—kinetics and thermodynamics, respectively—can be conceptually synthesized in an "energy landscape" paradigm: highly populated states and the kinetics of transitions between them can be described by the depths of energy wells and the heights of energy barriers, respectively. Local flexibility: atoms and residues Portions of protein s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parkinson's Disease
Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms become more common. The most obvious early symptoms are tremor, rigidity, slowness of movement, and difficulty with walking. Cognitive and behavioral problems may also occur with depression, anxiety, and apathy occurring in many people with PD. Parkinson's disease dementia becomes common in the advanced stages of the disease. Those with Parkinson's can also have problems with their sleep and sensory systems. The motor symptoms of the disease result from the death of cells in the substantia nigra, a region of the midbrain, leading to a dopamine deficit. The cause of this cell death is poorly understood, but involves the build-up of misfolded proteins into Lewy bodies in the neurons. Collectively, the main motor symptoms are also known as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alzheimer's Disease
Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term memory, remembering recent events. As the disease advances, symptoms can include primary progressive aphasia, problems with language, Orientation (mental), disorientation (including easily getting lost), mood swings, loss of motivation, self-neglect, and challenging behaviour, behavioral issues. As a person's condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the typical life expectancy following diagnosis is three to nine years. The cause of Alzheimer's disease is poorly understood. There are many environmental and genetic risk factors associated with its development. The strongest genetic risk factor is from an alle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amyloid
Amyloids are aggregates of proteins characterised by a Fibril, fibrillar morphology of 7–13 Nanometer, nm in diameter, a beta sheet (β-sheet) Secondary structure of proteins, secondary structure (known as cross-β) and ability to be Staining, stained by particular dyes, such as Congo red. In the human body, amyloids have been linked to the development of various diseases. Pathogenic amyloids form when previously healthy proteins lose their normal Protein structure, structure and physiology, physiological functions (Protein misfolding, misfolding) and form fibrous deposits in amyloid plaques around cells which can disrupt the healthy function of tissues and organs. Such amyloids have been associated with (but not necessarily as the cause of) more than 50 human diseases, known as amyloidosis, and may play a role in some neurodegenerative diseases. Some of these diseases are mainly sporadic and only a few cases are Genetic disorder, familial. Others are only Genetic disorder, fam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
