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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.
The introduction of the immunoelectrophoretic analysis gave a great boost to protein chemistry, some of the first results were the resolution of proteins in biological fluids and biological extracts. Among the important observations made were the great number of different proteins in serum, the existence of several immunoglobulin classes and ...
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.
Isomer shift can be expressed using the formula below, where K is a nuclear constant, the difference between R e 2 and R g 2 is the effective nuclear charge radius difference between excited state and the ground state, and the difference between [Ψ s 2 (0)] a and [Ψ s 2 (0)] b is the electron density difference in the nucleus (a = source, b ...
For example, butanol H 3 C−(CH 2) 3 −OH, methyl propyl ether H 3 C−(CH 2) 2 −O−CH 3, and diethyl ether (H 3 CCH 2 −) 2 O have the same molecular formula C 4 H 10 O but are three distinct structural isomers. The concept applies also to polyatomic ions with the same total charge. A classical example is the cyanate ion O=C=N − and ...
The atropisomer is an iodoaryl compound synthesised starting from (S)-valine and exists as the (M,S) isomer and the (P,S) isomer. The interconversion barrier between the two is 24.3 kcal/mol (101.7 kJ/mol). The (M,S) isomer can be obtained exclusively from this mixture by recrystallisation from hexanes.
According to some opinions, [6] [7] living eukaryotic cells perform isoelectric focusing of proteins in their interior to overcome a limitation of the rate of metabolic reaction by diffusion of enzymes and their reactants, and to regulate the rate of particular biochemical processes.
Isotopomers or isotopic isomers are isomers which differ by isotopic substitution, and which have the same number of atoms of each isotope but in a different arrangement. For example, CH 3 OD and CH 2 DOH are two isotopomers of monodeuterated methanol .