932 resultados para COOPERATIVE NUCLEATION


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The bacteriophage lambda repressor binds cooperatively to pairs of adjacent sites in the lambda chromosome, one repressor dimer binding to each site. The repressor's amino domain (that which mediates DNA binding) is connected to its carboxyl domain (that which mediates dimerization and the interaction between dimers) by a protease-sensitive linker region. We have generated a variant lambda repressor that lacks this linker region. We show that dimers of the variant protein are deficient in cooperative binding to sites at certain, but not all, distances. The linker region thus extends the range over which carboxyl domains of DNA-bound dimers can interact. In particular, the linker is required for cooperative binding to a pair of sites as found in the lambda chromosome, and thus is essential for the repressor's physiological function.

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We have prepared a family of peptide fragments of the 64-residue chymotrypsin inhibitor 2, corresponding to its progressive elongation from the N terminus. The growing polypeptide chain has little tendency to form stable structure until it is largely synthesized, and what structures are formed are nonnative and lack, in particular, the native secondary structural elements of alpha-helix and beta-sheet. These elements then develop as sufficient tertiary interactions are made in the nearly full-length chain. The growth of structure in the small module is highly cooperative and does not result from the hierarchical accretion of substructures.

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The extractive industry, more than any other sector of the economy, often finds itself mired in conflicts with various environmental and community interests. As traditional legal avenues of resolution gave way to the collaborative ideas of alternative dispute resolution, the outcomes, especially the relational outcomes, were less than desirable. This capstone project proposes that an Anticipatory Cooperative Effort (ACE) can help to bridge the gap between industry and environmental interests by encouraging a pro-active and pre-emptive engagement. The point of the ACE concept is not that it defines a new set of principles so much as it repositions where established ADR principles are entertained.

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The hexahydride complex OsH6(PiPr3)2 (1) activates the C–OMe bond of 1-(2-methoxy-2-oxoethyl)-3-methylimidazolium chloride (2), in addition to promoting the direct metalation of the imidazolium group, to afford a five-coordinate OsCl(acyl-NHC)(PiPr3)2 (3) compound. The latter coordinates carbon monoxide, oxygen, and molecular hydrogen to give the corresponding carbonyl (4), dioxygen (5), and dihydrogen (6) derivatives. Complex 3 also promotes the heterolytic bond activation of pinacolborane (HBpin), using the acyl oxygen atom as a pendant Lewis base. The hydride ligand and the Bpin substituent of the Fischer-type carbene of the resulting complex 7 activate the O–H bond of alcohols and water. As a consequence, complex 3 is a metal ligand cooperating catalyst for the generation of molecular hydrogen, by means of both the alcoholysis and hydrolysis of pinacolborane, via the intermediates 7 and 6.

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Cooperative learning has been successfully implemented in the last 60 years for teaching at different educational levels including the Higher Studies due to its solid theoretical foundation, the principles it proposes and its practical applications. The purpose of this article is to offer a proposal for some cooperative activities that allow students to work in small groups in a language subject in order to learn not only contents but also putting into practice what they learn, i.e., they learn by being active. This article discusses how the said activities make it possible for students to work with the main principles of cooperative learning, i.e.: positive interdependence, face-to-face interaction, individual and group accountability, interpersonal and small-group skills and group processing. Moreover, this research will also point out that the proposed activities allow students to acquire some of the social competences required in the labour market such as leadership, conflict solving and cooperation.

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Cooperative learning allows students acquisition of competences that are essential for the labour market such as leadership, critical thinking, communication, and so on. For this reason, different cooperative activities were designed in a language subject in English Studies so that students could work in groups and acquire those competences. This article describes some such activities and the emotional competences that students acquire with them. Moreover, a survey was conducted in order to establish students’ opinions about the main competences they acquired with the activities designed and their opinion about a cooperative methodology. Students’ answers were positive and they were aware of what they had learned.