Receptors recognition

however, pertinent to mention here that steric complimentarily is an absolute necessity, but eertainly not a suffieient evidence for ultimate recognition. It is indeed regarded to be a second-order effect, and do not represent a dominant one. 

The three aforesaid complimentarity (or similarity) may be legitimately confined to steric aspects (J.e., shape), electrostatic status i.e., distribution of-ve and +ve charges within the ligand-receptor system), and finally the hydrogen-bonding i.e., hydrophobic characteristic feature of the system). 

Salient Features The various salient features with respect to the ligand-receptor recognition 

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Comparison of thiazole-based regioisomers (464) and (465) has revealed a marked preference for the phenyl substitution of the former, a trend also observed in the subsequent imidazole series (data not shown), but not in the triazole series as evident from the data presented for (466) and (467) (Table 6.40). The thiazole (464) was approximately 8-fold less potent than the corresponding imidazole (470) (Table 6.41) suggesting that the seemingly subtle change of the central scaffold imparts a marked change in CBi receptor recognition. 

Two points need to be emphasized concerning the data on ACh release. First, PCP, etoxadrol, and cyclazocine are very potent, being effective in the same range in which they compete with 3H-PCP for binding to the PCP/sigma receptor recognition site. 

Kossiakoff, A. A. and De Vos, A. M., Structural basis for cytokine hormone-receptor recognition and receptor activation, Adv. Protein Chem., 52, 67-108, 1998. 

Beauchamp, C.O., Gonias, S.L., Menapace, D.P., and Pizzo, S.V. (1983) A new procedure for the synthesis of polyethylene glycol-protein adducts Effects on function, receptor recognition, and clearance of superoxide dismutase, lactoferrin, and a2macroglobulin. Anal. Biochem. 131, 25-33. 

Characterization of the GABAa Receptor Recognition Site Through Ligand Design and Pharmacophore Modeling... 

Thus, it is possible that apo(a) interacts with apo-B100 close to the LDL-receptor recognition site (Zl). 

Alvarez-Dominguez, C., Vazquez-Boland, J. A., Carrasco-Martin, E., Lopez-Mato, P., and Leyva-Cobain, E. (1997). Host cell heparan sulfate proteoglycans mediate attachment and entry of Listeria monocytongenes, and the listerial surface protein ActA is involved in heparan sulfate receptor recognition. Infect. Immun. 65, 78-88. 

Korhonen, T. K., Valtonen, M. V., Parrkinen, J., Vaisanen-Rhen, V., Finne, J., Orskov, L, Svenson, S. B., and Makela, P. H. (1985). Serotypes, hemolysin production, and receptor recognition of Escherichia coli strains associated with neonatal sepsis and meningitis. Infect. Immun. 48,486-491. 

Thankavel, K., Madison, B., Ikeda, T., Malaviya, R., Shah, A. H., Arumugen, P. M., and Abraham, S. N. (1997). Localization of a domain in the FimH adhesin of Escherichia coli type 1 fimbriae capable of receptor recognition and use of a domain-specific antibody to confer protection against experimental urinary tract infection. /. Clin. Invest. 100, 1123-1126. 

Albeit a high specificity of receptor recognition, affinities of individual receptor fragments are often rather low [1,5]. However, as receptors form clusters on host cell surfaces, the avidity increases. The low affinity of individual Hgands lends itself well to the appHcation of Hgand-based NMR techniques. 

Probably the smallest sequence known to be responsible for receptor recognition is the RGD-tripeptide, initially discovered in fibronectin [143]. However, the specificity of the interaction with different integrins, the counter receptors of RGD sequences on the cell surface, is established by the flanking sequences of the RGD motif and the conformation of the tripeptide. In other words, the presentation of the RGD sequence is important for specific recognition by individual integrins. 

Like the geometry around the metal center, the geometry in the backbone can also be important in receptor recognition. This has been extensively probed by synthetic... 

The closely related structures show completely different microbial uptake characteristics. The 3D structures described above show distinct different orientation of the backbone amide (tangental in type 1 versus radial in type 2), which can be explained by the interactions that take place between the FhuA receptor and the ferrichrome siderophore -As mentioned, the second coordination sphere of natural ferrichrome in FhuA receptor is very sensitive to the distance and orientation between a proton donor and the proton acceptor, therefore the orientation of the amide groups in the biomimetic siderophore plays a crucial role in receptor recognition. 

Since the 1,2-HOPO chelators form neutral complexes while the catecholates form charged complexes, it is reasonable to assume that charged species are essential for the enterobactin receptor recognition. The lack of recognition by the ferrichrome analog may well be attributed to the bulky substituents on the hydroxamate moiety in agreement with early observations by Emery and Emery and others ... 

These results imply that additional factors, such as charge and bulkiness, in addition to those described above, affect receptor recognition and should be taken into consideration during the design of improved siderophore mimics. 

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