1,720,997 research outputs found
esterase 2
No full textThe moderate thermophilic eubacterium Alicyclobacillus (formerly Bacillus) acidocaldarius expresses a thermostable
carboxylesterase ~esterase 2! belonging to the hormone-sensitive lipase ~HSL!-like group of the esterase0lipase family.
Based on secondary structures predictions and a secondary structure-driven multiple sequence alignment with remote
homologous protein of known three-dimensional ~3D! structure, we previously hypothesized for this enzyme the
a0b-hydrolase fold typical of several lipases and esterases and identified Ser155, Asp252, and His282 as the putative
members of the catalytic triad. In this paper we report the construction of a 3D model for this enzyme based on the
structure of mouse acetylcholinesterase complexed with fasciculin. The model reveals the topological organization of
the fold corroborating our predictions. As regarding the active-site residues, Ser155, Asp252, and His282 are located
close to each other at hydrogen bond distances. Their catalytic role was here probed by biochemical and mutagenic
studies. Moreover, on the basis of the secondary structure-driven multiple sequence alignment and the 3D structural
model, a residue supposed important for catalysis, Gly84, was mutated to Ser. The activity of the mutated enzyme was
drastically reduced. We propose that Gly84 is part of a putative “oxyanion hole” involved in the stabilization of the
transition state similar to the C group of the esterase0lipase family
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
A Sperm Nuclear Basic Protein from the Sperm of the Marine Worm Chaetopterus variopedatus with Sequence Similarity to the Arginine-Rich C-Termini of Chordate Protamine-Likes.
No full textThe sperm nuclear basic proteins (SNBPs) of the marine annelid worm Chaetopterus variopedatus have been shown previously to consist of a mixture of two SNBPs: histone H1-like (CvH1) and C.variopedatus protamine-like (CvPL). Here, we report the structural characterization of CvPL. The protein has a molecular weight of 8370.5 Da, a K/R ratio of 0.34, and a secondary structure, which are intermediate between those of protamine (P) and protamine-like (PL) SNBPs. The N-terminal sequence of CvPL shows a high extent of similarity with the arginine-rich C-terminal domain of chordate PL-type SNBPs. Furthermore, the protein binds to DNA in a similar fashion as vertebrate PLs and their own CvH1, but in a way that is different from that of the lysine-rich somatic H1 histones. We have experimentally determined the molar ratio CvH1:CvPL to be ∼1:6 in C. variopedatus sperm. Based on all of these, a model is proposed for the organization of the sperm chromatin by CvH1 and CvPL
New C16 fatty-acid-based oxylipin pathway in the marine diatom Thalassiosira rotula
No full textAn unprecedented series of C16 oxylipins (1–8) has been characterized from the marine diatom Thalassiosira rotula.
Absolute stereochemistry of the major alcohols 2 and 3 was determined to be 9S by spectroscopic and chemical
methods. All the described products are formally derived by unprecedented enzymatic oxidation of C16 fatty acids.
Conversion of hexadeca-6,9,12-trienoic acid (C16:3 x-4) into 3 unequivocally established the occurrence of (at least)
a specific 9S-oxygenase activity. To the best of our knowledge, the present data reveal for the first time the existence
of an organic network of oxygenase-mediated transformations that require C16 fatty acids as substrates in living cells
Point-of-care diagnostics of covid-19: From current work to future perspectives
Full text linkCoronaviruses have received global concern since 2003, when an outbreak caused by SARS‐CoV emerged in China. Later on, in 2012, the Middle‐East respiratory syndrome spread in Saudi Arabia, caused by MERS‐CoV. Currently, the global crisis is caused by the pandemic SARS‐ CoV‐2, which belongs to the same lineage of SARS‐CoV. In response to the urgent need of diagnostic tools, several lab‐based and biosensing techniques have been proposed so far. Five main areas have been individuated and discussed in terms of their strengths and weaknesses. The cell‐culture detection and the microneutralization tests are still considered highly reliable methods. The genetic screening, featuring the well‐established Real‐time polymerase chain reaction (RT‐PCR), represents the gold standard for virus detection in nasopharyngeal swabs. On the other side, immunoassays were developed, either by screening/antigen recognition of IgM/IgG or by detecting the whole virus, in blood and sera. Next, proteomic mass‐spectrometry (MS)‐based methodologies have also been proposed for the analysis of swab samples. Finally, virus-biosensing devices were efficiently designed. Both electrochemical immunosensors and eye‐based technologies have been described, showing detection times lower than 10 min after swab introduction. Alternative to swab‐based techniques, lateral flow point‐of‐care immunoassays are already commercially available for the analysis of blood samples. Such biosensing devices hold the advantage of being portable for on‐site testing in hospitals, airports, and hotspots, virtually without any sample treatment or complicated lab precautions
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
Functional and structural properties of the homogeneous beta-glycosidase from the extreme thermoacidophilic archaeon sulfolobus solfataricus expressed in Saccharomyces cerevisiae
No full textSDS-RESISTANT ACTIVE AND TERMOSTABLE DIMERS ARE OBTAINED FROM THE DISSOCIACION OF HOMOTETRAMERIC BETA-GLYCOSIDASE FROM HYPERTHERMOPHYLIC SULFOLOBUS SOLFATARICUS IN SDS. STABILIZING ROLE OF THE A-C INTERMONOMERIC INTERFACE
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