1,720,991 research outputs found
The interaction of rhodium compounds with proteins: A structural overview
No full textRhodium compounds have been used as scaffold for enzyme inhibitors, modulators of protein/protein interactions and of protein aggregation. These compounds have been investigated in their reaction with peptides and proteins with the aim to create artificial metalloenzymes with enhanced catalytic features. Despite several studies have been carried out in this context, the interactions occurring between Rh compounds and these biological molecules and the mechanisms that are responsible for the formation of Rh/peptides and Rh/protein adducts are still largely unknown. This review describes and analyzes the known structures of complexes between protein and Rh compounds and of Rh/protein adducts deposited in the Protein Data Bank. Artificial metalloenzymes are frequently formed by anchoring Rh compounds to proteins via covalent linkage strategies. However, new biohybrids can also be formed by dative anchoring, since coordinative bonds of protein residue side chains with Rh centers (and non-covalent interactions between protein atoms and Rh ligands) can occur. In these adducts, Rh centers preferentially bind the side chains of His, Asp, Asn, Lys and the C-terminal carboxylate. Our analysis provides interesting implications for the design of Rh-based artificial metalloenzymes
Interaction of Platinum-based Drugs with Proteins: An Overview of Representative Crystallographic Studies
No full textPt-based drugs are widely used in clinics for the treatment of cancer. The mechanism of action of these molecules relies on their interaction with DNA. However, the recognition of these metal compounds by proteins plays an important role in defining pharmacokinetics, side effects and their overall pharmacological profiles. Single crystal X-ray diffraction studies provided important information on the molecular mechanisms at the basis of this process. Here, the molecular structures of representative adducts obtained upon reaction with proteins of selected Pt-based drugs, including cisplatin, carboplatin and oxaliplatin, are briefly described and comparatively examined. Data indicate that metal ligands play a significant role in driving the reaction of Pt compounds with proteins; non-covalent interactions that occur in the early steps of Pt compound/protein recognition process play a crucial role in defining the structure of the final Pt-protein adduct. In the metallated protein structures, Pt centers coordinate few protein side chains, such as His, Met, Cys, Asp, Glu and Lys residues upon releasing labile ligands
Protein-metallodrugs interactions: Effects on the overall protein structure and characterization of Au, Ru and Pt binding sites
No full textThe effects of metalation process by inorganic compounds containing Au, Pt and Ru on protein structure and on conformation and flexibility of the residues involved in the metal compound binding have been here investigated by analysing 204 structures of protein/metallodrug adducts and the corresponding metal-free forms. The overall structure of the proteins is not significantly affected by the metal label. 162 non-redundant protein residues involved in Au, Pt and Ru coordination have been identified. In the metal-free protein structures these residues often belong to α-helical regions and show low flexibility. They do not necessarily belong to outer layers of the protein structure. In the majority of the adducts, the side chains of these residues adopt a conformation that is similar to that observed in the metal-free protein. The metal coordination reduces their solvent accessible surface area without altering their overall flexibility. These results could be useful for the prediction of residues able to bind Au, Pt and Ru compounds
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
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