Mimicry structural

Ballesteros, J. A., Shi, L., and Javitch, J. A., Structural mimicry in G-protein-coupled receptors implications of the high-resolution structure of rhodopsin for structure-function analysis of rhodopsin-like receptors, Mol. Pharmacol., 60(1), 1-19, 2001. 

Wiseman H, Cannon M, Arnstein HR, Barlow DJ (1992a) The structural mimicry of membrane sterols by tamoxifen evidence from cholesterol coefficients and molecular-modelling for its action as a membrane anti-oxidant and an anti-cancer agent. Biochim Biophys Acta 1138(3) 197-202... 

K. T. Holman, M. D. Ward, Metric Engineering of Crystalline Inclusion Compounds by Structural Mimicry , Angew. Chem. Int. Ed, 2000, 39,1653-1656. 

Another feature that we may refer to here is that of structural mimicry (52). It is generally accepted that a necessary and sufficient condition for formation of solid-solution crystals by two or more organic substances is similarity of shapes and sizes of the component molecules (53). Consider the two molecules salicylidene-lV-4-chloroaniline and -4-bromoaniline, which are very similar chemically and, in solution, structurally. Both are dimorphic, with molecules... 

These results imply that the type of behavior exhibited by a given system is not necessarily an intrinsic property of the system. It may, in fact, be possible in many cases to switch between two types of behavior by control of the reaction conditions, as it is for 124 and 129. In the context of this review the interesting aspect is that in such cases one would be able to determine whether the conformation of the product is determined by structural mimicry in the parent phase or by the intermolecular interactions in the crystal of the product. 

Fig. 4 Stereo views (in transparent, space-filling models) of selected hydrophobic interactions in the Fab-peptide and -pentasaccharide complexes. A Trp P3 buried in the hydrophobic cavity formed by CDR L3, His H58 and Trp H47. B Interactions of the side chain of Met P5 with Trp H33. C and D Interactions of the peptide and pentasaccharide, respectively, with His L27D and Tyr L32 (the pocket which accommodates the GlcNAc D methyl group). In (C) the hydrogen bond between the Asp P2 side chain and His L27D NE2 is also shown. A corresponding hydrogen bond between Rha Al 3-OH and His L27D NE2, shown in (D), represents an element of structural mimicry. Reproduced from [80]. 2003 by The National Academy of Sciences of the USA...

Taken together, these results suggest that molecular recognition of the dodecapeptide by antibodies differs from its recognition by concanavahn A, and that the immunological cross-reactivity observed in some studies does not reflect structural mimicry. That molecular recognition by concanavalin A of carbohydrates and peptides differs has also been shown in structural studies. Here, the functional molecular mimicry observed with respect to different receptors should not be assumed to imply structural mimicry—the inter-molecular interactions may differ in each case. 

Finally, the CG and CD atoms of the arginine residue of the tail occupy the positions of C3 and C4 of the + 1 GlcNAc residue. Thus, this arrangement may be considered structural mimicry, and one side of the - 1 sugar residue as well as part of the + 1 sugar residue are mimicked effectively by the peptide. 

Structural mimicry of the substrate is also observed in the complex between PPA and the proteinaceous inhibitor tendamistat [173]. Again, the inhibitor extends into the catalytic site, but contacts only one of the catalytic residues, the glutamate residue. The sequence of three residues of the inhibitor, WRY (Trp-18 to Tyr-20) is positioned in the active site, with the arginine residue forming hydrogen bonds with the catalytic Glu-233. The WRY sequence and residues Thr-55, Gly-59 and Tyr-60 make hydrophobic contacts with the active site which are similar to those of acarbose and of a-All. 

Nevertheless, the potential for autoimmune disease would clearly exist if one considers the polyspecificity of immune recognition molecules such as B cell receptors, antibodies, T cell receptors and MHC molecules. Further, the polyspecificity of immune receptors is also able to transcend the biochemically defined classes of biomolecules. For instance, the monoclonal antibody SYA/J6 has been demonstrated to have a dual specificity, binding a specific carbohydrate or a specific peptide with comparable affinity.68 Detailed analysis of the interatomic interactions between the antibody combining site and either the carbohydrate or the peptide antigens demonstrated that functional mimicry is possible without exact structural mimicry. This example underlines the case that it is not possible to predict with certainty whether the molecular surfaces of all potentially cross-reactive epitopes, whether of foreign or self molecules, will, or will not, be able to bind to a specific antibody. 

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