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The equilibrium between conformational isomers can be observed using a variety of spectroscopic techniques. Protein folding also generates conformers which can be observed. The Karplus equation relates the dihedral angle of vicinal protons to their J-coupling constants as measured by NMR.
Conformational isomerism is a form of isomerism that describes the phenomenon of molecules with the same structural formula but with different shapes due to rotations about one or more bonds. [12] [13] Different conformations can have different energies, can usually interconvert, and are very rarely isolatable.
Stereochemistry, a subdiscipline of chemistry, studies the spatial arrangement of atoms that form the structure of molecules and their manipulation. [1] The study of stereochemistry focuses on the relationships between stereoisomers, which are defined as having the same molecular formula and sequence of bonded atoms (constitution) but differing in the geometric positioning of the atoms in space.
Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural (or constitutional) isomerism, in which bonds between the atoms differ; and stereoisomerism or (spatial isomerism), in which the bonds are the same but the relative positions of the atoms differ. Isomeric relationships form a ...
The term, "flip" is misleading, because the direction of each carbon remains the same; what changes is the orientation. A conformation is a unique structural arrangement of atoms, in particular one achieved through the rotation of single bonds. [2] A conformer is a conformational isomer, a blend of the two words.
A pure substance is composed of only one type of isomer of a molecule (all have the same geometrical structure). Structural isomers have the same chemical formula but different physical arrangements, often forming alternate molecular geometries with very different properties. The atoms are not bonded (connected) together in the same orders.
The gauche effect is very sensitive to solvent effects, due to the large difference in polarity between the two conformers.For example, 2,3-dinitro-2,3-dimethylbutane, which in the solid state exists only in the gauche conformation, prefers the gauche conformer in benzene solution by a ratio of 79:21, but in carbon tetrachloride, it prefers the anti conformer by a ratio of 58:42. [9]
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, [1] or protein [2] which binds to the DNA double helix.