Look up lability in Wiktionary, the free dictionary.
Lability refers to something that is constantly undergoing change or is likely to undergo change. It is the opposite (antonym) of stability.
Lability refers to something that is constantly undergoing change or is likely to undergo change. It is the opposite (antonym) of stability.
In reference to biochemistry, this is an important concept as far as kinetics is concerned in metalloproteins. This can allow for the rapid synthesis and degradation of substrates in biological systems.
Labile cells refer to cells that constantly divide by entering and remaining in the cell cycle. [1] These are contrasted with "stable cells" and "permanent cells".
An important example of this is in the epithelium of the cornea, where cells divide at the basal level and move upwards, and the topmost cells die and fall off.
In medicine, the term "labile" means susceptible to alteration or destruction. For example, a heat-labile protein is one that can be changed or destroyed at high temperatures.
The opposite of labile in this context is "stable". [2]
Compounds or materials that are easily transformed (often by biological activity) are termed labile. For example, labile phosphate is that fraction of soil phosphate that is readily transformed into soluble or plant-available phosphate. [3] Labile organic matter is the soil organic matter that is easily decomposed by microorganisms. [4]
The term is used to describe a transient chemical species. As a general example, if a molecule exists in a particular conformation for a short lifetime, before adopting a lower energy conformation (structural arrangement), the former molecular structure is said to have 'high lability' (such as C25, a 25-carbon fullerene spheroid). The term is sometimes also used in reference to reactivity – for example, a complex that quickly reaches equilibrium in solution is said to be labile (with respect to that solution). Another common example is the cis effect in organometallic chemistry, which is the labilization of CO ligands in the cis position of octahedral transition metal complexes.
In chemistry, an ester is a compound derived from an acid in which the hydrogen atom (H) of at least one acidic hydroxyl group of that acid is replaced by an organyl group. These compounds contain a distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well, but not according to the IUPAC.
Cis–trans isomerism, also known as geometric isomerism, describes certain arrangements of atoms within molecules. The prefixes "cis" and "trans" are from Latin: "this side of" and "the other side of", respectively. In the context of chemistry, cis indicates that the functional groups (substituents) are on the same side of some plane, while trans conveys that they are on opposing (transverse) sides. Cis–trans isomers are stereoisomers, that is, pairs of molecules which have the same formula but whose functional groups are in different orientations in three-dimensional space. Cis and trans isomers occur both in organic molecules and in inorganic coordination complexes. Cis and trans descriptors are not used for cases of conformational isomerism where the two geometric forms easily interconvert, such as most open-chain single-bonded structures; instead, the terms "syn" and "anti" are used.
Physical science is a branch of natural science that studies non-living systems, in contrast to life science. It in turn has many branches, each referred to as a "physical science", together is called the "physical sciences".
In chemistry, a zwitterion, also called an inner salt or dipolar ion, is a molecule that contains an equal number of positively and negatively charged functional groups. 1,2-dipolar compounds, such as ylides, are sometimes excluded from the definition.
The equilibrium constant of a chemical reaction is the value of its reaction quotient at chemical equilibrium, a state approached by a dynamic chemical system after sufficient time has elapsed at which its composition has no measurable tendency towards further change. For a given set of reaction conditions, the equilibrium constant is independent of the initial analytical concentrations of the reactant and product species in the mixture. Thus, given the initial composition of a system, known equilibrium constant values can be used to determine the composition of the system at equilibrium. However, reaction parameters like temperature, solvent, and ionic strength may all influence the value of the equilibrium constant.
Bioenergetics is a field in biochemistry and cell biology that concerns energy flow through living systems. This is an active area of biological research that includes the study of the transformation of energy in living organisms and the study of thousands of different cellular processes such as cellular respiration and the many other metabolic and enzymatic processes that lead to production and utilization of energy in forms such as adenosine triphosphate (ATP) molecules. That is, the goal of bioenergetics is to describe how living organisms acquire and transform energy in order to perform biological work. The study of metabolic pathways is thus essential to bioenergetics.
Cyclohexane conformations are any of several three-dimensional shapes adopted by cyclohexane. Because many compounds feature structurally similar six-membered rings, the structure and dynamics of cyclohexane are important prototypes of a wide range of compounds.
ATP hydrolysis is the catabolic reaction process by which chemical energy that has been stored in the high-energy phosphoanhydride bonds in adenosine triphosphate (ATP) is released after splitting these bonds, for example in muscles, by producing work in the form of mechanical energy. The product is adenosine diphosphate (ADP) and an inorganic phosphate (Pi). ADP can be further hydrolyzed to give energy, adenosine monophosphate (AMP), and another inorganic phosphate (Pi). ATP hydrolysis is the final link between the energy derived from food or sunlight and useful work such as muscle contraction, the establishment of electrochemical gradients across membranes, and biosynthetic processes necessary to maintain life.
In chemistry, rotamers are chemical species that differ from one another primarily due to rotations about one or more single bonds. Various arrangements of atoms in a molecule that differ by rotation about single bonds can also be referred to as different conformations. Conformers/rotamers differ little in their energies, so they are almost never separable in a practical sense. Rotations about single bonds are subject to small energy barriers. When the time scale for interconversion is long enough for isolation of individual rotamers, the species are termed atropisomers. The ring-flip of substituted cyclohexanes constitutes a common form of conformers.
In chemistry, a molecule experiences strain when its chemical structure undergoes some stress which raises its internal energy in comparison to a strain-free reference compound. The internal energy of a molecule consists of all the energy stored within it. A strained molecule has an additional amount of internal energy which an unstrained molecule does not. This extra internal energy, or strain energy, can be likened to a compressed spring. Much like a compressed spring must be held in place to prevent release of its potential energy, a molecule can be held in an energetically unfavorable conformation by the bonds within that molecule. Without the bonds holding the conformation in place, the strain energy would be released.
The Curtin–Hammett principle is a principle in chemical kinetics proposed by David Yarrow Curtin and Louis Plack Hammett. It states that, for a reaction that has a pair of reactive intermediates or reactants that interconvert rapidly, each going irreversibly to a different product, the product ratio will depend both on the difference in energy between the two conformers and the energy barriers from each of the rapidly equilibrating isomers to their respective products. Stated another way, the product distribution reflects the difference in energy between the two rate-limiting transition states. As a result, the product distribution will not necessarily reflect the equilibrium distribution of the two intermediates. The Curtin–Hammett principle has been invoked to explain selectivity in a variety of stereo- and regioselective reactions. The relationship between the (apparent) rate constants and equilibrium constant is known as the Winstein-Holness equation.
A photoswitch is a type of molecule that can change its structural geometry and chemical properties upon irradiation with electromagnetic radiation. Although often used interchangeably with the term molecular machine, a switch does not perform work upon a change in its shape whereas a machine does. However, photochromic compounds are the necessary building blocks for light driven molecular motors and machines. Upon irradiation with light, photoisomerization about double bonds in the molecule can lead to changes in the cis- or trans- configuration. These photochromic molecules are being considered for a range of applications.
A cyclic compound is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where all the atoms are carbon, none of the atoms are carbon, or where both carbon and non-carbon atoms are present. Depending on the ring size, the bond order of the individual links between ring atoms, and their arrangements within the rings, carbocyclic and heterocyclic compounds may be aromatic or non-aromatic; in the latter case, they may vary from being fully saturated to having varying numbers of multiple bonds between the ring atoms. Because of the tremendous diversity allowed, in combination, by the valences of common atoms and their ability to form rings, the number of possible cyclic structures, even of small size numbers in the many billions.
Dissolved organic carbon (DOC) is the fraction of organic carbon operationally defined as that which can pass through a filter with a pore size typically between 0.22 and 0.7 micrometers. The fraction remaining on the filter is called particulate organic carbon (POC).
Diimide, also called diazene or diimine, is a compound having the formula HN=NH. It exists as two geometric isomers, E (trans) and Z (cis). The term diazene is more common for organic derivatives of diimide. Thus, azobenzene is an example of an organic diazene.
Physical organic chemistry, a term coined by Louis Hammett in 1940, refers to a discipline of organic chemistry that focuses on the relationship between chemical structures and reactivity, in particular, applying experimental tools of physical chemistry to the study of organic molecules. Specific focal points of study include the rates of organic reactions, the relative chemical stabilities of the starting materials, reactive intermediates, transition states, and products of chemical reactions, and non-covalent aspects of solvation and molecular interactions that influence chemical reactivity. Such studies provide theoretical and practical frameworks to understand how changes in structure in solution or solid-state contexts impact reaction mechanism and rate for each organic reaction of interest.
This glossary of chemistry terms is a list of terms and definitions relevant to chemistry, including chemical laws, diagrams and formulae, laboratory tools, glassware, and equipment. Chemistry is a physical science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions; it features an extensive vocabulary and a significant amount of jargon.
In chemistry, chemical stability is the thermodynamic stability of a chemical system, in particular a chemical compound or a polymer.
trans-Cyclooctene is a cyclic hydrocarbon with the formula [–(CH2)6CH=CH–], where the two C–C single bonds adjacent to the double bond are on opposite sides of the latter's plane. It is a colorless liquid with a disagreeable odor.
2,5-Diketopiperazine is an organic compound with the formula (NHCH2C(O))2. The compound features a six-membered ring containing two amide groups at opposite positions in the ring. It was first compound containing a peptide bond to be characterized by X-ray crystallography in 1938. It is the parent of a large class of 2,5-Diketopiperazines (2,5-DKPs) with the formula (NHCH2(R)C(O))2 (R = H, CH3, etc.). They are ubiquitous peptide in nature. They are often found in fermentation broths and yeast cultures as well as embedded in larger more complex architectures in a variety of natural products as well as several drugs. In addition, they are often produced as degradation products of polypeptides, especially in processed foods and beverages. They have also been identified in the contents of comets.
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