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(ek'sō-sī'klik, -sik'lik),
Relating to atoms or groups attached to a cyclic structure but not themselves cyclic, for example, the methyl group of toluene. Compare: endocyclic.
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References in periodicals archive ?
If the MBT anions intercalated in the LDH galleries are released into the damaged area through an ion-exchange process, with [Cl.sup.-] anions and O[H.sup.-] produced by cathode reduction, the MBT will be chemically adsorbed on the surface of the Q345 steel via the exocyclic S and N atoms, either in the form of thione or in the form of thiol structure.
The most note worthy feature of the hetrocyclic ring is the asymmetry of the exocyclic angles at N(1A) [i30.80[degrees]1.
Now the fact that can1 > -6.77 and can2 > -16.82 for the acidic 5'-GMP gel strongly suggests that the sugar pucker conformation is exclusively C3'-endo with the exocyclic [gamma]-torsion angle being in the gg conformation [10-12]; see Figure S2 in the Supporting Information.
Matsushima et al., "Human DNA glycosylase enzyme TDG repairs thymine mispaired with exocyclic etheno-DNA adducts," Free Radical Biology and Medicine, vol.
Therefore, in reactions of 2-aminothiazole and its 4-phenyl derivative with chloroformates, acyl halides, and anhydrides the exocyclic nitrogen is the main nucleophilic center which is in agreement with the reported literature [32].
The details of the reaction are somewhat beyond the scope of this article; essentially, normal cytosine has a C=C double bond which is sensitive to addition of a sulfate group from the bisulphite ion; this sulfate group weakens the exocyclic amine group and leads to its hydrolytic loss, thereby replacing the -NH2 with =0, which defines the difference between cytosine and uracil bases.
The aldehyde residue of abasic sites can generate an interstrand crosslink by reacting with the exocyclic amino group of a guanine base (34).
The melamine reacts with up to six formaldehyde groups to form two methylol groups on each exocyclic amine group.
The mass fragmentation pattern of the ligands ([L.sup.1])-([L.sup.3]) followed the cleavage of C=N (exocyclic), C=C, and C-O bonds.
Subsequently, with the aim of investigating the role played by the exocyclic region in the receptor interaction, a series of truncated peptides related to hU-II has been investigated.
The sesquiterpene aromadendrene bears a reactive exocyclic methylene group and a cyclopropane ring which can alkylate proteins and thereby disturb the conformation of protein.
MDA is an aldehyde capable of interacting with DNA to form exocyclic adducts, including 3-(2-deoxy-[beta]-D-erythro-pentafuranosyl) pyrimido [1,2-[alpha]] purin-10(3H)-one deoxyguanosine ([M.sub.1]dG).