Compartmental ligands, functions

A broad application of phenolic Sehiff base ligands lies in the synthesis of heterobimetallic complexes. Extended functionalization of the L2 - ligand affords the so-called compartmental ligands which ensure rich coordination chemistry by accomodation of several metals [89, 146]. Some representative ligands are depicted in Fig. 25. 

In this model, OBPs participate in the selective transport of pheromone and other semiochemicals to their olfactory receptors. The selectivity of the system is likely to be achieved by layers of filters [ 16], i.e., by the participation of compartmentalized OBPs and olfactory receptors. It seems that OBPs transport only a subset of compounds that reach the pore tubules. Some of these compounds may not bind to the receptors compartmentalized in the particular sensilla. The odorant receptors, on the other hand, are activated by a subset of compounds, as indicated by studies in Drosophila, showing that a single OR is activated by multiple compounds [66]. If some potential receptor ligand reaches the pore tubules but are not transported by OBPs, receptor firing is prevented because the receptors are protected by the sensillar lymph. In other words, even if neither OBPs nor odorant receptors (ORs) are extremely specific, the detectors (olfactory system) can show remarkable selectivity if they function in a two-step filter. 

Wu M, Holowka D, Craighead HG, Baird B. Visualization of plasma membrane compartmentalization with patterned lipid bilayers. Proc. Natl. Acad. Sci. U.S.A. 2004 101 13798-13803. Marlin SD, Springer TA. Purifled intercellular adhesion molecule-1 (ICAM-1) is a ligand for lymphocyte function-associated antigen 1 (LEA-1). Cell 1987 51 813-819. 

Recently, the novel design of compartmental Schiff bases has led to the incorporation of crown ether moieties into the macrocyclic structure. One such ligand containing an N3O2 Schiff base and a 020 ( = 3 [H2LA] or 4 [H2LB]) crown-ether functionality (see Figure 73) have been used to... 

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