Synthetic membranes spectra

Ciclopirox olamine is a synthetic broad-spectrum antimycotic agent with inhibitory activity against dermatophytes, Candida species, and P orbiculare. This agent appears to inhibit the uptake of precursors of macromolecular synthesis the site of action is probably the fungal cell membrane. 

The action spectrum of the photoresponse was first reported by Tien s group [5] and was confirmed by Ilani and Berns [4] as being similar to the absorption spectrum of chlorophyll. The implication is that chlorophyll is an essential component of the photosensitive BLM. Mangel et al. [6] have demonstrated that completely synthetic membranes consisting of purified phosphatidyl choline, carotenoid and chlorophyll a have photovoltaic properties similar to those reported for chloroplast extract BLM. More important, it was demonstrated that all three components are needed to produce the sustained photoresponse. The intensity of the photocurrent produced was also reported to be a function of chlorophyll and carotenoid concentration in the membrane-forming solution. 

The spin label technique appeared to be very fruitful recently in research ofmembrane-carotenoids interaction. The shape of a spin probe ESR spectrum is sensitive to the rate of its molecular motion being directly dependent on the membrane fluidity determined by the rate of lipid molecular motion. Thus, the analysis of ESR spectra of spin labels doped into pigmented membranes would provide information on the carotenoid effect on particular regions of lipid bilayers, dependent on the type of probes applied, penetrating different membrane portions. Tfiis technique was applied to study an effect of xanthophylls and j8-carotene on fluidity of lipid membranes formed with several synthetic and nonsaturated phosphatidylcholines (Subczynski et al, 1991,1992,1993 StrzalkaandGruszecki, 1991, Yin and Subczynski, 1996, Wisniewska and... 

Finally, in an attempt to avoid the multiple intracellular resistance mechanisms that bacteria have evolved to inactivate AGs, several studies have demonstrated the potential of the positively charged AGs to be used as scalfolds for the development of membrane-targeting cationic amphiphilic antimicrobial agents. In these derivatives, hydrophobic residues are attached to one or more positions on the AG [23-25]. Several synthetic directions to develop AG-based cationic amphiphiles that wiU act as membrane-targeting antibiotics have resulted in AG derivatives with broad-spectrum activity against pathogenic bacteria with high levels of resistance to AGs and different levels of specificity for bacterial relative to eukaryotic membranes. 

CP-MAS has allowed the study of conformations and cross-linkages in natural and synthetic polymers, and of structures of proteins, nucleic acids, phospholipid membranes, etc. The field is still in its infancy and its applications will undoubtedly grow. The CP-MAS solid state C-NMR spectrum of 19S-vindolinine, has been studied by Atta-ur-Rahman and coworkers at H.E.J. Research Institute of Chemistry, and it is shown in Figure 4.16. It represents the first example of a CP-MAS spectrum of a solid Aspidosperma alkaloid ever recorded. 

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