from the free oligonucleotide and the complex with paromomycin. Fragment ions were detected for the free oligonucleotide but not for the complex. The authors suggest that this lack of fragmentation was because binding of paromomycin produced a change in the local charge distribution, conformation, or mobility at the deoxyadenosine sites that precluded activation and fragmentation. Two combinatorial libraries containing 216 tetraazacyclophanes were mixed with the chimeric oligonucleotide. More than 10 complexes between the oligonucleotide and members of the library with the same nominal mass were observed. CAD of the most abundant complex generated three fragment ions resulting from cleavage at each of the deoxyadenosine residues. The fragmentation pattern revealed both the mass and binding site of the ligand. The second most abundant complex yielded few fragment ions during CAD indicating that it must bind at the model A site region as did paramomycin This MS-based assay allows identification of the binding sites for small ligands without the use of labels (/ Am Chem Soc 1 9 9 9 121 474-75)
Imaging particles
imaging of trace species on the particles. Nevertheless, the data show evidence of localized It is quite a mystery why increased concenchemical variation across the surface. trations of small airborne particulate matter, Images had a pixel resolution of 10 um especially those with aerodynamic diameters after smoothing. The of
