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331.
MSn experiments involving low energy collisionally activated dissociation (CAD) in a quadrupole ion trap were used to characterize
the fragmentation of alkali, alkaline earth and transition metal complexes of five cyclic peptides, and the results were compared
with those obtained for protonated cyclic peptides. Complexes with metal ions produced enhanced abundances of the most diagnostic
fragments for elucidating the primary structures. For cyclosporin A, nickel and lithium complexes gave additional sequence
information compared with the protonated peptide. For depsipeptides, sodium and lead complexes were superior to the protonated
peptide or other metal complexes for sequencing residues, and CAD of the lead complexes led to preferential cleavage of two
residues at a time. For cyclic lipopeptides, complexes with silver, nickel and strontium ions provided enhanced abundances
of key fragment ions. 相似文献
332.
Teshome B. Yisgedu Xuenian Chen Hima K. Lingam Zhenguo Huang Edward A. Meyers Sheldon G. Shore Ji‐Cheng Zhao 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(1):m1-m3
The asymmetric unit of the title salt, 2NH4+·B10H102−·1.5H2O or (NH4)2B10H10·1.5H2O, (I), contains two B10H102− anions, four NH4+ cations and three water molecules. (I) was converted to the anhydrous compound (NH4)2B10H10, (II), by heating to 343 K and its X‐ray powder pattern was obtained. The extended structure of (I) shows two types of hydrogen‐bonding interactions (N—H...O and O—H...O) and two types of dihydrogen‐bonding interactions (N—H...H—B and O—H...H—B). The N—H...H—B dihydrogen bonding forms a two‐dimensional sheet structure, and hydrogen bonding (N—H...O and O—H...O) and O—H...H—B dihydrogen bonding link the respective sheets to form a three‐dimensional polymeric network structure. Compound (II) has been shown to form a polymer with the accompanying loss of H2 at a faster rate than (NH4)2B12H12 and we believe that this is due to the stronger dihydrogen‐bonding interactions shown in the hydrate (I). 相似文献
333.
Sheldon Yoshio Okada Raz Jelinek Deborah Charych 《Angewandte Chemie (International ed. in English)》1999,38(5):655-659
A blue to red color change is induced on addition of phospholipase A2 to modified PDA vesicles 1 (PDA=polydiacetylene). This bathochromic transition results from chemical modification of the vesicles by hydrolysis of the enzyme substrate embedded in the PDA matrix. Addition of a known phospholipase inhibitor or removal of Ca2+ ions suppresses the color change, which suggests the potential for applications in high‐throughput screening assays. 相似文献
334.
Schmidke WB Abrams GS Matteuzzi C Amidei D Baden AR Barklow T Boyarski AM Boyer J Breidenbach M Burchat PR Burke DL Butler F Dieterle WE Dorfan JM Feldman GJ Gidal G Gladney L Gold MS Goldhaber G Golding LJ Haggerty J Hanson G Hayes K Herrup D Hollebeek RJ Innes WR Jaros JA Juricic I Kadyk JA Karlen D Klein SR Lankford AJ Larsen RR LeClaire BW Levi ME Lockyer NS Lüth V Nelson ME Ong RA Perl ML Richter B Riles K Ross MC Rowson PC Schaad T Schellman H Sheldon PD Trilling GH de la Vaissiere C 《Physical review letters》1986,57(5):527-530
335.
Wormser G Abrams G Amidei D Baden AR Barklow T Boyarski AM Boyer J Burchat PR Burke DL Butler F Dorfan JM Feldman GJ Gidal G Gladney L Gold MS Goldhaber G Golding L Haggerty J Hanson G Hayes K Herrup D Hollebeek RJ Innes WR Jaros JA Juricic I Kadyk JA Karlen D Klein SR Lankford AJ Larsen RR LeClaire BW Levi M Lockyer NS Lüth V Nelson ME Ong RA Perl ML Richter B Riles K Rowson PC Schaad T Schellman H Schmidke WB Sheldon PD Trilling GH Wood DR Yelton JM 《Physical review letters》1988,61(9):1057-1060
336.
Sheldon Axler Zeljko Cuckovic N. V. Rao 《Proceedings of the American Mathematical Society》2000,128(7):1951-1953
In this note we show that if two Toeplitz operators on a Bergman space commute and the symbol of one of them is analytic and nonconstant, then the other one is also analytic.
337.
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