1,721,116 research outputs found
Hemocyanin subunit organization of the gastropod Rapana thomasiana
No full textRtH1 and RtH2, the two hemocyanin isoforms of the prosobranch gastropod Rapana thomasiana, have been purified by anion-exchange chromatography and studied by SDS-PAGE and immunoelectrophoresis. Both subunit types are built up of eight functional units (FUs). Under reducing conditions subunit RtH2 splits into two fragments, RtH2-a-f and RtH2-gh, suggesting the presence of a disulfide bridge between FU2-f and FU2-g. By proteolytic cleavage of the subunits into three-, two-, and single-FU fragments, purification of fragments by HPLC, N-terminal sequencing of the peptides, and crossed-line immunoelectrophoresis, FUs-a-h of RtH2 and FU-a, FU-d, FU-e, and FU-f of RtH1 were identified and correlated to the eight-FUs pattern of immunoelectrophoresis. FU-a, FU-e, and FU-f of RtH1 and RtH2 are very closely related immunologically. RtH1 and RtH2 both correspond immunologically to KLH2, one of the two hemocyanin isoforms of the prosobranch gastropod Megathura crenulata
Characterization of the carbohydrate moieties of the functional unit RvH(1)-a of Rapana venosa haemocyanin using HPLC/electrospray ionization MS and glycosidase digestion
No full textThe primary structures of two biantennary N-glycans of the
glycoprotein Rapana venosa (marine snail) haemocyaninwere determined. Two different structural subunits have been found in R. venosa haemocyanin: RvH1 and RvH2. The carbohydrate content of the N-terminal functional unit RvH1-a of RvH1 was studied and compared with the N-terminal functional unit RvH2-a of RvH2. Oligosaccharide fragments were released from the glycoprotein by Smith degradation of a haemocyanin pronase digest and separated on a Superdex 300 column. The glycopeptide fragments, giving a positive reaction for the orcinol/H2SO4 method, were separated by HPLC. In order to determine the linked sugar chains to the hinge glycopeptides isolated from the functional unit RvH1-a, several techniques were applied, including capillary electrophoresis, matrix-assisted laser desorption ionization-MS
and electrospray ionization-MS in combination with glycosidase
digestion. On the basis of these results and amino acid sequence analysis, we concluded that the functional unit RvH1-a contains 7% oligosaccharides N-glycosidically attached to Asn262 and Asn401, and the following structures were suggested
ADVANCES IN REVERSE TRANSCRIPTION POLYMERASE CHAIN REACTION ANALYSIS OF CELLULAR mRNA LEVELS OF TRANSFORMING GROWTH FACTOR-BETA1 BY CAPILLARY ELECTROPHORESIS WITH LASER-INDUCED FLUORESCENCE DETECTION.
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Development of Mass Spectrometric and Chromatographic Micro Methods for the Analysis of Protein Phosphorylations
No full textEs wurden massenspektrometrische und chromatographische Mikro-Methoden zur Analyse von Proteinphosphorylierungen entwickelt und im Bereich der Insulin-
Signaltransduktion angewendet. Zunächst wurden Proteom-analytische Methoden (im Gel-Verdau, Proteinidentifizierung) entwickelt, untersucht und zur Analyse der b-
UE des HIR eingesetzt. Zur Aufreinigung und Konzentration von Peptiden und Phosphopeptiden wurden neue RP- sowie IMAC-Mikro-Tip-Techniken entwickelt.
Desweiteren wurden die Phosphopeptid-spezifischen Neutralverlust- und Vorläuferionen-Scantechniken (Triple-Quad-MS) untersucht und verglichen. Zur
Lokalisierung von Phosphorylierungsstellen wurde zudem die NanoES-MS2 untersucht und ein neues MS3-Verfahren (API- und q2-CID) vorgestellt. Die
Scantechniken wurden zur Identifizierung der Phosphorylierungen von b-Casein (< 5 pmol) eingesetzt. Zur effizienten Analyse von Phosphopeptiden wurden off- und
on-line-µIMAC/ES-MS-Verfahren entwickelt. Desweiteren wurde eine Phosphopeptid-spezifisches alkalisches µLC/ESI-API-CID-Hybrid-Scan-Verfahren
entwickelt und zur Analyse von b-Casein eingesetzt. Mit Hilfe der LC- und MS-Verfahren wurden schließlich Phosphoproteine aus dem Bereich der Insulin-
Signaltransduktion analysiert. Mittels [32P]-RP-HPLC-Phosphopeptid-Mapping konnte gezeigt werden, dass 'in vivo' Ser1177/78/82 des HIR für die
Autophosphorylierung des Rezeptors entbehrlich, für die Substratphosphorylierung aber notwendig sind. Mittels m/z 79-Vorläuferionen-Analyse konnten die
Phosphorylierungen der b-UE des 'in vivo'-insulinstimulierten HIR-WT detektiert werden. Die 'in vitro'-Substratspezifität von PKC-Subtypen wurde mittels on-line-
UV-µLC/ESI-MS semiquantitativ untersucht. Mit einem neu entwickelten [32P]-2-D-RP-HPLC/Mikro-ESI/MS-Verfahren und off-line-NanoES-Ionenfallen-MS3
wurde das 'in vitro' mit PKC-bI und -z umgesetzte GST-IRS-1Nk-Fusionsprotein analysiert und eine Phosphorylierung an Ser318 (IRS-1-Sequenz) ermittelt.Mass spectrometric and chromatographic micro-methods have been developed and applied for the analysis of insulin-signalling phosphoproteins. The proteom-analytical methods (in-gel digest, protein identification) were first developed, investigated and applied to the analysis of the HIR-b-subunit. New RP- and IMAC micro tip techniques for the purification and enrichment of peptides and phosphopeptides were developed. Furthermore, the phosphopeptide specific neutral loss and precursor ion scan techniques (Triple-Quad-MS) have been investigated and compared. For the localization of phosphorylation sites NanoES-MS2 was investigated and a new MS3-based method (API- and q2-CID) was also developed. The scan techniques were applied for the identification of the phosphorylation sites from b-casein (< 5 pmol). For the efficient analysis of phosphopeptides off- and on-line-µIMAC/ES-MS-methods have been developed. Furthermore, a phosphopeptide specific alkaline µLC/ESI-API-CID hybrid scan method was developed which was applied for the analysis of b-casein. The LC- and MS-based methods were then used for the analysis of insulin-signalling phosphoproteins. Using [32P]-RP-HPLC phosphopeptide mapping we showed, that Ser1177/78/82 of the HIR were in vivo not essential for receptor autophosphorylation but necessary for substrate phosphorylation. The phosphorylation sites of the b-subunit of the in vivo insulin stimulated HIR-WT could be detected using m/z 79 precursor ion scanning. Using on-line UV-µLC/ESI-MS the in vitro substrate specifity of PKC isoforms was investigated in a semiquantitative way. In vitro with PKC-bI and -z treated GST-IRS-1Nk-fusionsprotein was analysed by using a new developed [32P]-2-D-RP-HPLC/micro-ESI/MS method and off-line NanoES-ion-trap-MS3. At Ser318 (IRS-1-sequence) a phosphorylation site was detected, which could play a major role in insulin signal transduction
- …
