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  2. Cyclic symmetry in three dimensions - Wikipedia

    en.wikipedia.org/wiki/Cyclic_symmetry_in_three...

    It has reflection symmetry with respect to a plane perpendicular to the n-fold rotation axis. C nv, [n], (*nn) of order 2n - pyramidal symmetry or full acro-n-gonal group (abstract group Dih n); in biology C 2v is called biradial symmetry. For n=1 we have again C s (1*). It has vertical mirror planes. This is the symmetry group for a regular n ...

  3. Protomer - Wikipedia

    en.wikipedia.org/wiki/Protomer

    In structural biology, a protomer is the structural unit of an oligomeric protein. It is the smallest unit composed of at least one protein chain. The protomers associate to form a larger oligomer of two or more copies of this unit. Protomers usually arrange in cyclic symmetry to form closed point group symmetries.

  4. Electrocyclic reaction - Wikipedia

    en.wikipedia.org/wiki/Electrocyclic_reaction

    Correlation diagrams, which connect the molecular orbitals of the reactant to those of the product having the same symmetry, can then be constructed for the two processes. [ 3 ] These correlation diagrams indicate that only a conrotatory ring opening of 3,4-dimethylcyclobutene is symmetry allowed whereas only a disrotatory ring opening of 5,6 ...

  5. Point groups in three dimensions - Wikipedia

    en.wikipedia.org/wiki/Point_groups_in_three...

    The conjugacy definition would also allow a mirror image of the structure, but this is not needed, the structure itself is achiral. For example, if a symmetry group contains a 3-fold axis of rotation, it contains rotations in two opposite directions. (The structure is chiral for 11 pairs of space groups with a screw axis.)

  6. Pericyclic reaction - Wikipedia

    en.wikipedia.org/wiki/Pericyclic_reaction

    Example of a pericycle reaction: the norcaradiene–cyclohexatriene rearrangement. In organic chemistry, a pericyclic reaction is the type of organic reaction wherein the transition state of the molecule has a cyclic geometry, the reaction progresses in a concerted fashion, and the bond orbitals involved in the reaction overlap in a continuous cycle at the transition state.

  7. Circular permutation in proteins - Wikipedia

    en.wikipedia.org/wiki/Circular_permutation_in...

    The CyBase database collects proteins that are cyclic, some of which are permuted variants of cyclic wild-type proteins. [10] SISYPHUS is a database that contains a collection of hand-curated manual alignments of proteins with non-trivial relationships, several of which have circular permutations.

  8. Desymmetrization - Wikipedia

    en.wikipedia.org/wiki/Desymmetrization

    The precursor benzil has C 2v symmetry, and the product is C 2 symmetric. Citric acid is also a symmetric molecule that can be desymmetrized by partial methylation. Desymmetrization of citric acid. The alcoholysis of cyclic anhydrides can be conducted enantiosymmetrically using chiral amine catalysts. [6]

  9. Cycloaddition - Wikipedia

    en.wikipedia.org/wiki/Cycloaddition

    In organic chemistry, a cycloaddition is a chemical reaction in which "two or more unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity". The resulting reaction is a cyclization reaction.