Lipophilic contact

Courtship behavior of Dysdera crocata, a specialized feeder on woodlice (Pso-coptera), is released by contact with nest silk or the cuticle of a live or even dead female. Washing with ether rendered these substrates inactive, suggesting the presence of a lipophilic contact pheromone (Pollard et al., 1987). 

Chemical functionality (positive ionizable area, lipophilic contact) without geometric constraint +++ -... 

Points Lipophilic Contacts and Charge-transfer Interactions... 

Both lipophilic contacts and charge-transfer interactions represent layer 4 features and are implemented as 3D points with a specified tolerance. 

Figure 2 Role of water molecules in hydrogen bonds (upper part) and lipophilic interactions (lower part). In the unbound state (left side), the polar groups of the ligand and the protein form hydrogen bonds to water molecules. These water molecules are replaced upon complex formation. The hydrogen-bond inventory (total number of hydrogen bonds) does not change. In contrast, the formation of lipophilic contact increases the total number of hydrogen bonds due to the release of water molecules from the unfavorable lipophilic environment.

Figure 13. Design of orally active inhibitors of elastase at Zeneca. The initial idea, to replace the Ala-Pro unit by a pyridone, led to 10. Later, pyrimidones were investigated. In this structural class, very potent elastase inhibitors were found, e.g., 12. Very good in vivo properties are observed for 13. The p-flu-orophenyl- or p-aminophenyl substituent improves the lipophilic contact with the enzyme.

The defence secretions of the species with labral brushes are lipophilic contact poisons (Prestwich, 1979, Prestwich and Collins, 1982). The major component of the soldier secretion of Prorhinotermes simplex is a nitrogenous compound, 1-nitro-tra/w-pentadecene (Vrkoc and Ubic, 1974). Schedorhino-termes putorius produces three ketones, l-tetradecen-4-one, l-hexadecen-3-one, and 2-tridecanone ((Juennedey et al., 1973). Similar ketones have been found in S. lamanianus (Prestwich et al., 1975), the main component in both... 

The replacement of the second galactose moiety in trisaccharide 70 by 1,2-dideoxy-Gal in 78 (entry 9) raised the affinity close to that of tetrasaccharide 67 (rIP 0.76 vs 1.0). When the similar modification was applied to the pseudo-tetrasaccharides 75-77, improved affinities were obtained for the (/ )- and (5)-lactic acid derivatives 79 and 80 (entries 10 and 11), but not for the phenyllactic acid derivative 81 (entry 12). For further investigating the lipophilic contact emanating from the a(2-6)-linked NeuSAc residue [68], the 6-position of the /yxo-hexitol moiety was derivatized with lipophilic substituents. Whereas benzyl ether 82 (entry 13) turned out to be less active than tetrasaccharide 67, the biphenylmethyl derivative 83 (entry 14) proved to be superior. 

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