4,221 research outputs found

    Electron Detachment Dissociation,and Collision-Induced Dissociation of Polyamidoamine (PAMAM) Dendrimer Ions with Amino, Amidoethanol, and Sodium Carboxylate Surface Groups

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    Here, we investigate the effect of the structure (generation) and nature of the surface groups of different polyamidoamine (PAMAM) dendrimers on electron-mediated dissociation, either electron capture dissociation (ECD) or electron detachment dissociation (EDD), and compare the fragmentation with that observed in collision-induced dissociation (CID). ECD and EDD of the PAMAM dendrimers esulted in simple mass spectra, which are straightforward to interpret, whereas CID produced complex mass spectra. The results show that electron-mediated dissociation (ECD and EDD) of PAMAM dendrimers does not depend on the nature of the surface group but tends to occur within the innermost generations. CID of the PAMAM dendrimers showed a strong dependence on the nature of the surface group and occurred mostly in the outer generation. The results demonstrate the potential utility of ECD and EDD as a tool for the structural analysis of PAMAM dendrimers

    Top-Down Mass Analysis of Protein Tyrosine Nitration: Comparison of Electron Capture Dissociation with “Slow-Heating” Tandem Mass Spectrometry Methods

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    Tyrosine nitration in proteins is an important post-translational modification (PTM) linked to various pathological conditions. When multiple potential sites of nitration exist, tandem mass spectrometry (MS/MS) methods provide unique tools to locate the nitro-tyrosine(s) precisely. Electron capture dissociation (ECD) is a powerful MS/MS method, different in its mechanisms to the “slow-heating” threshold fragmentation methods, such as collision-induced dissociation (CID) and infrared multiphoton dissociation (IRMPD). Generally, ECD provides more homogeneous cleavage of the protein backbone and preserves labile PTMs. However recent studies in our laboratory demonstrated that ECD of doubly charged nitrated peptides is inhibited by the large electron affinity of the nitro group, while CID efficiency remains unaffected by nitration. Here, we have investigated the efficiency of ECD versus CID and IRMPD for top-down MS/MS analysis of multiply charged intact nitrated protein ions of myoglobin, lysozyme, and cytochrome c in a commercial Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. CID and IRMPD produced more cleavages in the vicinity of the sites of nitration than ECD. However the total number of ECD fragments was greater than those from CID or IRMPD, and many ECD fragments contained the site(s) of nitration. We conclude that ECD can be used in the top-down analysis of nitrated proteins, but precise localization of the sites of nitration may require either of the “slow-heating” methods

    Determinants Of Unionisation For Part-Time Women Employees In Australian Banks

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    Against the declining trend of Australian employees to join unions, unionisation of part-time female employees in the banking industry is relatively strong. For the finance and insurance industry in 2001, 30.3% of total part-time female employees were unionised compared to 25% of full-time female employees and 17.2% of full-time male employees. Overall, 22.3% of employees from this industry were members (ABS, 2002). Under freedom of association, what can influence an individual's decision to unionise? A survey was conducted on three major Australian banks in August 2000. We use a binary choice regression model to analyse personal and union-organising characteristics that significantly influence individual's decision to unionise. Previous membership under union preference provisions and earning relatively high wages would lead to a higher probability to join the union. Union's role in enterprise bargaining and whether union did anything to recruit have significant impact on individual decisions. Thus, part-time female employees are not unwilling to join when they recognise the need for job protection.

    Tissue, cell type and stage-specific ectopic gene expression and RNAi induction in the Drosophila testis

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    The Drosophila testis has numerous advantages for the study of basic cellular processes, as production of sperm requires a highly orchestrated and complex combination of morphological changes and developmentally regulated transitions. Experimental genetics using Drosophila melanogaster has advanced dramatically with the advent of systems for ectopic expression of genetic elements in specific cells. However the genetic tools used in Drosophila research have rarely been generated with the testes in mind, and the utility of relatively few systems has been documented for this tissue. Here I will summarize ectopic expression systems that are known to work for the testis, and provide advice for selection of the most appropriate expression system in specific experimental situations

    ORCID EPrints Implementation Survey Analysis

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    This report explores the results of a survey of users on their requirements and plans for integrating ORCID functionality into EPrints repository software. The community was invited to share their use cases, and an online survey based on this information was conducted to determine the priorities and needs of the wider community

    The Message of the Rose

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    The Wnt receptor Ryk is a negative regulator of mammalian dendrite morphogenesis

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    This work was supported by the National Health and Medical Research Council (NHMRC) of Australia (Grants 1061512, 1063080). ML and KS were supported by an Australian Postgraduate Award or a University of Queensland International Scholarship, respectively. Imaging work was performed in the Queensland Brain Institute’s Advanced Microscopy Facility and generously supported by an ARC LIEF ï»żgrant ï»ż(LE130100078). We thank Assoc. Prof. Julian Heng (Harry Perkins Institute of Medical Research, Perth, Australia) for providing the ï»żpCA-ß-EGFPm5-Silencer 3 vector, Prof. Joseph LoTurco (University of Connecticut, USA) for the piggyBAC vector, and Prof. Steven Stacker (Peter MacCallum Cancer Centre, Melbourne, Australia) for providing the Ryk knockout mice and the full-length Ryk plasmid. We are also grateful to Mr Luke Hammond for expert advice on microscopy and Ms Rowan Tweedale for critical reading of the manuscript.Peer reviewedPublisher PD

    Electron Capture Dissociation Mass Spectrometry of Metallo-Supramolecular Complexes

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    The electron capture dissociation (ECD) of metallo-supramolecular dinuclear triple-stranded helicate Fe2L3 4 ions was determined by Fourier transform ion cyclotron resonance mass spectrometry. Initial electron capture by the di-iron(II) triple helicate ions produces dinuclear double-stranded complexes analogous to those seen in solution with the monocationic metal centers CuI or AgI. The gas-phase fragmentation behavior [ECD, collision-induced dissociation (CID), and infrared multiphoton dissociation (IRMPD)] of the di-iron double-stranded complexes, (i.e., MS3 of the ECD product) was compared with the ECD, CID, and IRMPD of the CuI and AgI complexes generated from solution. The results suggest that iron-bound dimers may be of the formFeI 2L2 2 and that ECD by metallo-complexes allows access, in the gas phase,to oxidation states and coordination chemistry that cannot be accessed in solution