Bilayer motifs

Figure 2. The two layering motifs observed for guanidi-nium organomonosulfonate salts, (a) The " discrete bilayer" motif in which all of the organic groups project from the same side of a given GS sheet, (b) The "continuously interdigitated layer" motif, in which the organic groups on adjacent GS ribbons project to opposite sides of the sheet.

In the racemic crystal of (J S)-ValNCA, the molecules are packed in a bilayer motif perpendicular to the haxis ( Figure 8.13). The bilayers are composed of alternating parallel rows of R and S molecules, with a single sense of pxjlarity along the c-axis. 

The interfadal activity of amphiphiles is but one manifestation of their discordant intramolecular makeup. These molecules can also self-assemble in solution to form a variety of microstructures, such as micelles and vesicles to name a few. Of course structures based on a bilayer motif, such as vesicles, have direct biological relevance as they serve as models for cell membranes. 

Fu Z-Y, Wu X-T, Dai J-C, Wu L-M, Cui C-P, Hu S-M (2001) Interpenetration in [Cd (isonicotinate>2(l,2-bis(4-pytidyl)ethane)o.5(H20)]n, a novel octahedral polymer containing an unusiral two-dimensional bilayer motif generated by self-assembly of rectangle building blocks. Chem Commtm 1856... 

With the adequacy of lipid bilayer membranes as models for the basic structural motif and hence for the ion transport barrier of biological membranes, studies of channel and carrier ion transport mechanisms across such membranes become of central relevance to transport across cell membranes. The fundamental principles derived from these studies, however, have generality beyond the specific model systems. As noted above and as will be treated below, it is found that selective transport... 

Figure 3. Schematic representations of feasible pillared GS host frameworks, (a) Sterically demanding pillars force a continuous "brick" architecture characterized by GS sheets that are topologically homologous to the continuously interdigitated layer motif observed in some guanidinium organo-monosulfonate salts, (b) Sterically undemanding pillars can from either "discrete bilayer" or continuous brick architec-...

The structural adaptation exhibited by GS bilayer frameworks is achieved through a variety of mechanisms associated with the intrinsic conformational softness of the host framework, including (1) formation of a shifted-ribbon GS sheet motif (Figure 4h) in which adjacent ribbons are shifted from the quasihexagonal arrangement, by as much as ai/2, such that they are connected by one strong (G)N-H—O(S)... 

Doubly-Lipid Modified Protein Sequence Motifs Exhibit Long-Lived Anchorage to Lipid Bilayer Membranes, S. Shahinian, J. R. Silvius, Biochemistry 1995, 34, 3813-3822. 

The final steps in fusion are only incompletely understood. For instance, it is controversial whether the non-bilayer transition states in fusion are initiated primarily by force, transmitted from the pull of the assembling SNARE motifs via the linkers onto the membrane, as suggested by mutagenesis of the linker domain. Alternatively, the function of the SNARE motifs may be confined to close apposition of the membranes, with the final steps being catalyzed by other factors such as a... 

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