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Protein secondary structure is the local spatial conformation of the polypeptide backbone excluding the side chains. [1] The two most common secondary structural elements are alpha helices and beta sheets , though beta turns and omega loops occur as well.
The main chain–main chain hydrogen bond is replaced by a side chain–main chain hydrogen bond. 3D computer superimposition shows that, in proteins, they occur [12] as one of the same four types that beta turns do, except that their relative frequency of occurrence differs: type II’ is the most common, followed by types I, II and I’.
In chemistry, pyramidal inversion (also umbrella inversion) is a fluxional process in compounds with a pyramidal molecule, such as ammonia (NH 3) "turns inside out". [1] [2] It is a rapid oscillation of the atom and substituents, the molecule or ion passing through a planar transition state. [3]
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 ...
The main method of systematic nomenclature is to follow with square brackets containing the number of atoms in the smaller ring then the number of atoms in the larger ring, separated by a period, in each case excluding the spiroatom (the atom by which the two rings are bonded) itself.
Chemistry is the scientific study of the properties and behavior of matter. [1] It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances.
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition.
In chemistry, a salt bridge is a combination of two non-covalent interactions: hydrogen bonding and ionic bonding (Figure 1). Ion pairing is one of the most important noncovalent forces in chemistry, in biological systems, in different materials and in many applications such as ion pair chromatography. It is a most commonly observed ...