Ring structures, generation

Figure 2-106. Ring teinplates foc a saturated siy-inernbei ed cing and a six-ineinbeced ring with one double bond as implemented in the ring conformation table of the 3D structure generator CORINA.

In cyclic structures, ring closure has to be taken into account as an additional geometrical constraint of the 3D structure generation process. Ring closure dramatically reduces the degrees of freedom as expressed in a reduction in the... 

Conformation analysis methods. In many cases in the process of building a 3D structure from scratch, decisions have to be made between multiple alternatives with similar energy. A typical example is an sp -sp torsion angle with similar energies for the alternatives of -i-60°, -60° and 180°. In many cases, rules are used to decide (e.g. stretch an open chain portion as much as possible to avoid clashes). Sometimes, the best result cannot be determined without a conformation analysis (e.g. complex ring systems with exocycHc substituents). Despite conformation analysis being a topic of its own covered in the next chapter, many automatic 3D structure generators have to fall back in certain situations to a limited conformation search in order so solve a specific problem and to come up with a reasonable solution. 

Tricyclic antidepressant A family of first-generation (typical) antidepressants with a three-ringed structure that inhibit the action of monoamine transporters. 

Aromatic amines are initially metabolized by aromatic and A -hydroxylation (oxidation reactions) and Y-acetylation. Following aromatic ring hydroxylation, the ring structure may be further conjugated with glucuronic acid or sulfate (Parkinson 1996). N-hydroxylation results in the potential methemoglobin-generating metabolite,... 

As we have determined A (Hilb (P(E)/X)) in theorem 4.3.11, and its structure is in fact rather simple, this gives us a simple description of A (Hilb3(P(P)/X)), which is also very useful for computations. We now also want to describe this ring by generators and relations. Because the relations are very complicated, we don t want to state them all, but rather refer to [Gottsche (6)] for the list of all relations. 

A form of peptidomimetics (a peptidomimetic is a compound that acts as a substitute for peptides in their interaction with receptors) is the formation of DKPs where amino acid residues are cyclized to form a stable ring structure. The design and development of peptidomimetics allows for the generation of new pharma-cotherapeutic agents with the potential of exerting a more desirable or favorable physiological response than its prototype. ... 

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