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In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element – but distinct arrangements of atoms in space. [1] Isomerism refers to the existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties.
An example of an isozyme is glucokinase, a variant of hexokinase which is not inhibited by glucose 6-phosphate. Its different regulatory features and lower affinity for glucose (compared to other hexokinases), allow it to serve different functions in cells of specific organs, such as control of insulin release by the beta cells of the pancreas ...
The isomerization energy, for example, for converting from a stable cis isomer to the less stable trans isomer is greater than for the reverse reaction, explaining why in the absence of isomerases or an outside energy source such as ultraviolet radiation a given cis isomer tends to be present in greater amounts than the trans isomer.
In traditional names various qualifiers are used to label isomers, for example, isopropanol (IUPAC name: propan-2-ol) is an isomer of n-propanol (propan-1-ol). The term moiety has some overlap with the term "functional group". However, a moiety is an entire "half" of a molecule, which can be not only a single functional group, but also a larger ...
These include meso compounds, cis–trans isomers, E-Z isomers, and non-enantiomeric optical isomers. Diastereomers seldom have the same physical properties. In the example shown below, the meso form of tartaric acid forms a diastereomeric pair with both levo- and dextro-tartaric acids, which form an enantiomeric pair.
These isomers are common in biology and have many functions, for example taste sensory, regulating phosphate levels, metabolic flux, transcription, mRNA export and translation, insulin signaling, embryonic development and stress response. Cis-inositol is the only isomer not found naturally in nature. [14]
Porphycene, first porphyrin isomer, synthesised from bipyrrole dialdehyde through McMurry coupling reaction. The first synthetic porphyrin isomer was reported by Emanual Vogel and coworkers in 1986. [27] This isomer [18]porphyrin-(2.0.2.0) is named as porphycene, and the central N 4 Cavity forms a rectangle shape as shown in figure. [28]
In chemistry, isomerization or isomerisation is the process in which a molecule, polyatomic ion or molecular fragment is transformed into an isomer with a different chemical structure. [1] Enolization is an example of isomerization, as is tautomerization. [2] When the isomerization occurs intramolecularly it may be called a rearrangement reaction.