1,720,979 research outputs found
A new inhibitor of the transcription-termination factor Rho.
No full textIn this study we describe BI-K0058, a new inhibitor of the transcription-termination factor Rho belonging to a different chemical class from bicyclomycin, the only known antibiotic acting on Rho. BI-K0058 inhibits the poly(C)-dependent ATPase activity of Rho with an IC(50) of 25 microM as well as in vitro transcription-termination of two natural substrates, the Salmonella enterica hisG cistron and the f1 phage intergenic region. BI-K0058 does not affect photolabeling of Rho by ATP. The results of gel mobility shift experiments with a natural RNA substrate demonstrate that BI-K0058 inhibits the formation of the ATP-independent high affinity Rho-RNA complex
Biotransformation of lipoglycopeptide antibiotic A40926 by Actinoplanes teichomyceticus cells
No full textAssignment of the five disulfide bridges in an alpha-amylase inhibitor from wheat kernel by fast-atom-bombardment mass spectrometry and Edman degradation.
No full textThe assignment of the five disulfide bridges in an alpha-amylase monomeric inhibitor from wheat kernel (coded 0.28) was achieved by combining fast-atom-bombardment mass spectrometry (FAB-MS) and automatic sequencing based on Edman degradation. Direct FAB-MS analysis of the native and reduced enzymatic digests of the protein allowed the assignment of three disulfide bridges out of five, including those involving two adjacent cysteine residues. The remaining two disulfide bridges were assigned by sequencing automatically the peptide clusters purified from the tryptic digest of the native protein
Biotransformation of the lipoglycopeptide antibiotic A40926 by Actinoplanes teichomyceticus cells
No full textCompound A40926, produced by Actinomadura ATCC 39727, is a lipoglycopeptide antibiotic complex which inhibits Gram-positive bacteria and Neisseria species. Individual components of the complex have an identical glycopeptide core but differ in the acid chains attached to the amino group of the glucuronic moiety. Suspension cultures and resting cells of Actinoplanes teichomyceticus ATCC 31121 were able to deacylate compound A40926 factors to yield the glycopeptide nucleus, which can be then synthetically reacylated to form new analogs. In an optimized fedbatch deacylation process, 0.5 g L-1 of compound A40926 was almost completely converted into the deacyl derivative. Under the same conditions, deacylation was also accomplished with tert-butoxycarbonyl (tert-BOC) A40926, in which the amino group at C15 was blocked to prevent formation of diacyl analogs during reacylation. The deacylase is an endoenzyme whose preliminary characterization is presented. © 1995 Society for Industrial Microbiology
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
- …
