527 research outputs found
ATP Binding Causes a Conformational Change in the γ Subunit of the Escherichia coli F1ATPase Which Is Reversed on Bond Cleavage
No full textATP hydrolysis by the Escherichia coli F1 ATPase (ECF1) induces a conformational change in the subunit. This change can be monitored by fluorescence changes in N-[4-[7-(diethylamino)-4-methyl]coumarin-3-yl)]maleimide (CM) bound at a cysteine introduced by site-directed mutagenesis into the subunit at position 106 [Turina, P.,& Capaldi, R. A. (1994) J. Biol. Chem. 269, 13465–13471]. In studies reported here, the magnitude of the fluorescence change has been determined with the noncleavable nucleotide analogue AMP•PNP and by rapid measurements using the slowly cleavable ATPS.The data indicate that maximal fluorescence change occurs with binding of 1 mol of nucleotide triphosphate per mole of ECF1. During unisite catalysis, ATP binding causes a fluorescence enhancement from CM bound at position 106, which is then followed by fluorescence quenching. The kinetics of these fluorescence changes have been measured using both ATP and ATPS as substrate. With ATPS, these kinetics can be simulated using rate constants similar to those for ATP except for an approximately 30-fold slower rate of the bond cleavage and resynthesis steps, i.e., k+2 and k−2. The observed rates and amplitudes of the fluorescence changes on hydrolysis of ATP and ATPS were analyzed by simulations in which the bond cleavage or the Pi release step was responsible for fluorescence quenching. The results indicate that ATP or ATPS binding causes the fluorescence enhancement of CM bound to the γ subunit and that this conformational change is reversed upon bond cleavage to yield ADP•Pi or ADP•PiS in catalytic sites. © 1994, American Chemical Society. All rights reserved
Il dono alla città: espressioni di benevolentia nell’Italia romana.
No full textAlla luce di una rilettura di passi significativi del de officiis di Cicerone si sottolineano le relazioni tra la precettistica ciceroniana e la politica di Augusto e si formula una proposta circa le motivazioni propagandistiche delle iniziative del principe in campo edilizio
3d modelling for valorizing 20th century architectural archives: the case of the unbuilt project for a theatre in Cagliari by Carlo Mollino
No full textThe issue of conservation and valorisation of Cultural Heritage involves today 20th century architectural archives, that come to us with their often considerable amount of materials, where the predominance of the design drawings arises. Interpretation, fruition and sharing of archival materials aimed to deepening the knowledge of contemporary masters and architectural movements address the works of many international scholars. In particular, using the continuous innovations of digital modelling tools, a field of this research is developing reconstruction and new interpretations of masters’ unbuilt projects. The rise of H-BIM for modelling architectural heritage, has been flanked by some experiments really aimed to represent unbuilt architectures. This is the case presented in this paper: the unbuilt project for the “Teatro Comunale” in Cagliari, designed by Carlo Mollino between 1964 and 1965. The building has been digitally modelled and the potentialities of BIM tools are today in phase of evaluation, also in light of the aim to create a collection of reconstructive models of Mollino’s projects, to be shared on-line. In particular, in this phase of the research, we are exploring the potentiality of BIM aimed to evidencing the reliability of reconstructive modelling based on different documentary sources
Cuma al tempo dei Borbone tra scavi e collezioni di antichità
No full textBefore the discovery of Pompeii and Herculaneum, lovers of Neapolitan antiquities found in Phlaegrean Fields the precious objects which adorned their houses.
At Cumae ancient monuments were in a large part still visible and in the open country. These conditions drew Spanish viceroies’s attention. King Charles Bourbon, on the contrary, showed scarce interest. Bourbon glory was increased by the antiquities from Pompeii and Herculaneum, which raised the Court of Naples at the level of the most prestigious Courts in Europe. During a long time, the fame of Cumae derived from Vergilian poems and Sibylla’s fascination, more than from ancient ruins. Only from the middle of 19th century Cuma was systematically explorated by Leopold Bourbon Count of Syracuse, the brother of King Ferdinand II. Private and illegal excavations advanced parallelly, in order to feed a flourishing traffic of antiquities.
This article makes use of fresh evidences from archives, and reconstructs events and passages which led Cuman finds from excavations of 18th and 19th centuries, to private collections and foreign museums
Holistic Development
No full textThe way in which holistic development can be
pursued depends on how sustainable business
models are constructed by actors involved in the
value creation (Boons and Lüdeke-Freund 2013).
In this respect, consistent leadership models (i.e.,
ethical leadership and responsible leadership) are
crucial because entrepreneurs and managers play
a key role in shaping the organizational culture
and the decision-making process that affect their
everyday routine, as well as intra-organization
procedures and structures (Melé 2012; Del
Baldo 2016).
Ethical leadership rests on personal traits and
behaviors such as integrity and transparency in
communication with stakeholders (Brown 2005;
Capaldi 2013).
Responsible leadership facilitates the involvement
of stakeholders and the creation of a cohesive
internal and external community cemented
by values and moral convictions (Jones 2014).
The ‘pillars’ by which responsible leaders guide
the company toward holistic development include
stakeholder consideration, communication,
empowerment, inclusion, and long-term orientation
(Magni and Pennarola 2015).
In summary, holistic development rests on a
business model consistent with a leadership
model that allows companies to share a strategic
orientation toward an integrated development
paradigm
X-ray evidence of a native state with increased compactness populated by tryptophan-less B. licheniformis β-lactamase.
No full textβ-lactamases confer antibiotic resistance, one of the most serious world-wide health problems, and are an excellent theoretical and experimental model in the study of protein structure, dynamics and evolution. Bacillus licheniformis exo-small penicillinase (ESP) is a Class-A β-lactamase with three tryptophan residues located in the protein core. Here, we report the 1.7-Å resolution X-ray structure, catalytic parameters, and thermodynamic stability of ESP(ΔW), an engineered mutant of ESP in which phenylalanine replaces the wild-type tryptophan residues. The structure revealed no qualitative conformational changes compared with thirteen previously reported structures of B. licheniformis β-lactamases (RMSD = 0.4-1.2 Å). However, a closer scrutiny showed that the mutations result in an overall more compact structure, with most atoms shifted toward the geometric center of the molecule. Thus, ESP(ΔW) has a significantly smaller radius of gyration (R(g)) than the other B. licheniformis β-lactamases characterized so far. Indeed, ESP(ΔW) has the smallest R(g) among 126 Class-A β-lactamases in the Protein Data Bank (PDB). Other measures of compactness, like the number of atoms in fixed volumes and the number and average of noncovalent distances, confirmed the effect. ESP(ΔW) proves that the compactness of the native state can be enhanced by protein engineering and establishes a new lower limit to the compactness of the Class-A β-lactamase fold. As the condensation achieved by the native state is a paramount notion in protein folding, this result may contribute to a better understanding of how the sequence determines the conformational variability and thermodynamic stability of a given fold
Mediologie decameroniane. Boccaccio e le origini dello spazio letterario moderno = Mediology of Decameron: Boccaccio and the origins of the modern literary space
No full textHow to read a classic of literature such as the Decameron through a mediological approach? According to a first reflection on the general structure of the work, the author investigates the reasons making the text a decisive moment of rupture and innovation in the history of communication and culture. Main issues concern: Firstly, the medium's invention we are used to calling "literature", through the abandonment of the late medieval forms of written textuality. Significant changes in the medium's structure are related with the silent reading spread, and with the new social life complexity in cities. Secondly, the awareness of the reality-phenomenon ambiguity, and the consequent need to face it through a full sensorial experience: With Boccaccio emerged a revanche of the image, imagination, eros, in contrast with the pressure of the logical order of the normative and allegorical writing, and that opposition was regulated giving narrative expression to open conflicts. Thirdly, the introduction of a particular storytelling technology based on the ambiguity of discourse and situations, being interpreted on several levels. Finally, the spaces metaphorical values: Florence, the plague city, as an overturning for a new necessary beginning; and the garden in the "cornice", as a recognition of the subject sensitive nature in its relationship with the world
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