1,721,016 research outputs found
Thermodynamics of reduction of Chromatium vinosum high-potential iron-sulfur protein and its histidine depleted H42Q mutant
No full textThe thermodynamic parameters for the reduction reaction of the high-potential iron-sulfur protein from Chromatium vinosum, and its H42Q mutant, have been measured by direct cyclic voltammetry using a 'non-isothermal' reference electrode. Histidine 42 is mainly responsible for the pH dependence of the reduction potential (E degrees) with pK(a), values equal to 5.9 and 6.3 for the oxidized and reduced proteins, respectively. The H42Q mutant does not present this pH dependence, although an increasing E degrees at the lowest pH values is still present. The main contribution to the difference in free energy between the protonated and the neutral His42 forms is given by the enthalpic term (Delta Delta H degrees = 7.4 kJ mol(-1)), although the entropic term is not negligible. (C) 1998 Elsevier Science S.A. All rights reserved
The exploitation of a hempseed byproduct to produce flavorings and healthy food ingredients by a fermentation process
Full text linkFollowing the One Health principles in food science, the challenge to valorize byproducts from the industrial sector is open. Hemp (Cannabis sativa subsp. sativa) is considered an important icon of sustainability and as an alternative food source. Hemp seed bran, in particular, is a byproduct of industrial hemp seed processing, which is not yet valorized. The success, and a wider market diffusion of hemp seed for food applications, is hindered by its unpleasant taste, which is produced by certain compounds that generally overwhelm the pleasant bouquet of the fresh product. This research concerns the exploration of hemp seed bran through fermentation using beneficial lactobacilli, focusing on the sensorial and bioactive traits of the products when they are subjected to bacterial transformation. By studying of the aromatic profile formation during the fermentation process the aim was to modulate it in order to reduce off‐odors without affecting the presence of healthy volatile organic compounds (VOCs). Applying multivariate analyses, it was possible to target the contribution of processing parameters to the generation of flavoring and bioactive compounds. To conclude, the fermentation process proposed was able to reduce unpleasant VOCs, whilst at the same time keeping the healthy ones, and it also improved nutritional quality, depending on time and bacterial starters. The fermentation proposed was a sustainable biotechnological approach that fitted perfectly with the valorization of hemp byproducts from the perspective of a green‐oriented industrial process that avoids synthetic masking agents
Mechanism of Interaction of Niflumic Acid with Heterologously Expressed Kidney CLC-K Chloride Channels
No full textCLC-K Cl(-) channels belong to the CLC protein family. In kidney and inner ear, they are involved in transepithelial salt transport. Mutations in ClC-Kb lead to Bartter's syndrome, and mutations in the associated subunit barttin produce Bartter's syndrome and deafness. We have previously found that 3-phenyl-CPP blocks hClC-Ka and rClC-K1 from the extracellular side in the pore entrance. Recently, we have shown that niflumic acid (NFA), a nonsteroidal anti-inflammatory fenamate, produces biphasic behavior on human CLC-K channels that suggests the presence of two functionally different binding sites: an activating site and a blocking site. Here, we investigate in more detail the interaction of NFA on CLC-K channels. Mutants that altered block by 3-phenyl-2-(p-chlorophenoxy)propionic acid (CPP) had no effect on NFA block, indicating that the inhibition binding site of NFA is different from that of 3-phenyl-CPP and flufenamic acid. Moreover, NFA does not compete with extracellular Cl(-) ions, suggesting that the binding sites of NFA are not located deep in the pore. Differently from ClC-Ka, on the rat homologue ClC-K1, NFA has only an inhibitory effect. We developed a quantitative model to describe the complex action of NFA on ClC-Ka. The model predicts that ClC-Ka possesses two NFA binding sites: when only one site is occupied, NFA increases ClC-Ka currents, whereas the occupation of both binding sites leads to channel block
Experimental evidence for the role of buried polar groups in determining the reduction potential of metalloproteins: the S79P variant of Chromatium vinosum HiPIP
No full textThe amide group between residues 78 and 79 of Chromatium vinosum high-potential iron-sulfur protein (HiPIP) is in close proximity to the Fe4S4 cluster of this protein and interacts via a hydrogen bond with S gamma of Cys77, one of the cluster ligands, The reduction potential of the S79P variant was 104+/-3 mV lower than that of the recombinant wild-type (rcWT) HiPIP (5 mM phosphate, 100 mM NaCl, pH 7, 293 K), principally due to a decrease in the enthalpic term which favors the reduction of the rcWT protein. Analysis of the variant protein by NMR spectroscopy indicated that the substitution has little effect on the structure of the HiPIP or on the electron distribution in the oxidized cluster. Potential energy calculations indicate that the difference in reduction potential between rcWT and S79P variant HiPIPs is due to the different electrostatic properties of amide 79 in these two proteins, These results suggest that the influence of amide group 79 on the reduction potential of C, vinosum HiPIP is a manifestation of a general electrostatic effect rather than a specific interaction. More generally, these results provide experimental evidence for the importance of buried polar groups in determining the reduction potentials of metalloproteins
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
Industrial hemp foods and beverages and product properties
No full textHemp is a versatile, sustainable, and undemanding crop. Traditionally, plants of C. sativa L. were grown as a fiber crop to produce fabrics and ropes, while the seeds of this plant, regardless of their high nutritional value, were generally treated as a by-product and mainly intended for animals. Today, with the surge in studies related to the recognition of the nutritional characteristics of hemp seeds and its health benefits, the production of hemp seeds has increased and they have become a product with an important and growing market. Hemp seeds and hemp seed-based products are, in fact, attractive for those consumers looking for sustainable and eco-sustainable food products with high nutritional value, those suffering from celiac disease (CeD) and lactose intolerance, as well as for vegans and athletes. Hemp seeds have commonly been claimed as a nutritionally complete food source that can be eaten whole as whole seed or as shelled or hulled seeds, as well as processed into a variety of food products, including beverages and baked goods
Prediction of astringency in red wine using tribology approach to study in-mouth perception
Full text link- …
