Semihydrogenation of 1,2-bis(3,4-dicyanophenyl)ethyne gave cis-1,2-bis(3,4-dicyanophenyl)ethene. From these precursors, binuclear phthalocyanines were produced containing linear binuclear phthalocyanines having an ethyne bridge and a mixture of cis and trans isomers of binuclear phthalocyanines linked by an ethene bridge. The cis and trans isomers could be separated and differentiated by gel permeation chromatography as the very extended trans isomer elutes faster than the cofacial globular cis isomer. Strong coupling between the conjugated binuclear phthalocyanine was not observed when examined by cyclic voltammetry. Key words: phthalocyanines, cofacial, binuclear, cyclic voltammetry.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and structure determination of the adducts of the potent carcinogen 7,12-dimethylbenz[a]anthracene and deoxyribonucleosides formed by electrochemical oxidation: models for metabolic activation by one-electron oxidationN. V. S. RamaKrishna, Ercole L. Cavalieri, E. G. Rogan, G. Dolnikowski, R. L. Cerny, M. L. Gross, H. Jeong, R. Jankowiak, and G. J. SmallCite this: J. Am. Chem. Soc. 1992, 114, 5, 1863–1874Publication Date (Print):February 1, 1992Publication History Published online1 May 2002Published inissue 1 February 1992https://pubs.acs.org/doi/10.1021/ja00031a047https://doi.org/10.1021/ja00031a047research-articleACS PublicationsRequest reuse permissionsArticle Views143Altmetric-Citations41LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAntineoplastic agents. 190. Isolation and structure of the cyclodepsipeptide dolastatin 14George R. Pettit, Yoshiaki Kamano, Cherry L. Herald, Claude Dufresne, Robert B. Bates, Jean M. Schmidt, Ronald L. Cerny, and Haruhisa KizuCite this: J. Org. Chem. 1990, 55, 10, 2989–2990Publication Date (Print):May 1, 1990Publication History Published online1 May 2002Published inissue 1 May 1990https://pubs.acs.org/doi/10.1021/jo00297a001https://doi.org/10.1021/jo00297a001research-articleACS PublicationsRequest reuse permissionsArticle Views204Altmetric-Citations51LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Abstract The mass spectrometric detection limits for guanine, adenine, and an adeninddimethylbenthracene adduct were greatly improved by converting the materials to pentafluorobenzyl derivatives, as well as by doing coaxial continuous flow-FAB (coaxial cf-Fast Atom Bombardment). The lowest detection limit (approximately 10 pg) was achieved when the derivatized sample was introduced by coaxial cf-FAB and the determination was by fill-scan mass spectrometry. The lowest detection limit achieved by tandem mass spectrometry was 50 pg obtained after derivatization, coaxial cf-FAB introduction and detection with an extended mass range array. Key Words: Tandem MSarray detectorPAH-DNA adductscoaxial cf-FABderivatizationdetection limit.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComparison of fast atom bombardment and field desorption mass spectrometry of coordination complexesRonald L. Cerny, B. Patrick. Sullivan, Maurice M. Bursey, and Thomas J. MeyerCite this: Anal. Chem. 1983, 55, 12, 1954–1958Publication Date (Print):October 1, 1983Publication History Published online1 May 2002Published inissue 1 October 1983https://pubs.acs.org/doi/10.1021/ac00262a028https://doi.org/10.1021/ac00262a028research-articleACS PublicationsRequest reuse permissionsArticle Views90Altmetric-Citations37LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Abstract Neurofibrillary tangles, which are major pathological hallmarks of Alzheimer's disease (AD), are composed of paired helical filaments (PHFs) containing hyperphosphorylated tau. Specific kinases regulate tau phosphorylation and are closely linked to the pathogenesis of AD. We have characterized a human tau‐tubulin kinase 1 ( TTBK1 ) gene located on chromosome 6p21.1. TTBK1 is a serine/threonine/tyrosine kinase that is conserved among species and belongs to the casein kinase 1 superfamily. It is specifically expressed in the brain, especially in the cytoplasm of cortical and hippocampal neurons. TTBK1 phosphorylates tau proteins in both a Mg 2+ ‐ and a Mn 2+ ‐dependent manner. Phosphopeptide mapping and immunoblotting analysis confirmed a direct tau phosphorylation by TTBK1 at Ser198, Ser199, Ser202 and Ser422, which are also phosphorylated in PHFs. TTBK1 also induces tau aggregation in human neuronal cells in a dose‐dependent manner. We conclude that TTBK1 is a neuron‐specific dual kinase involved in tau phosphorylation at AD‐related sites and is also associated with tau aggregation.
Molecular weights of macrolide antibiotics can be determined from either (M + H)(+) or (M + Met)(+), the latter desorbed from alkali metal salt-saturated matrices. The ion chemistry of macrolides, as determined by tandem mass spectrometry (MS/MS), is different for ions produced as metallated than those formed as (M + H)(+) species. An explanation for these differences is the location of the charge. For protonated species, the charge is most likely situated on a functional group with high proton affinity, such as the dimethylamino group of the ammo sugar. The alkali metal ion, however, is bonded to the highly oxygenated aglycone. As a result, the collision-activated dissociation spectra of protonated macrolides are simple with readily identifiable fragment ions in both the high and low mass regions but no fragments in the middle mass range. In contrast, the cationized species give complex spectra with many abundant ions, most of which are located in the high mass range. The complementary nature of the fragmentation of these two species recommends the study of both by MS/MS when determining the structure or confirming the identity of these biomaterials.
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