1,039 research outputs found
Synthesis of photoactivable probes for the study of glycosphingolipid-protein interactions
No full textSYNTHESIS OF PHOTOACTIVABLE PROBES FOR THE STUDY OF GLYCOSPHINGOLIPID-PROTEIN INTERACTIONS
Giuseppina Brasile,1 Federica Compostella,1 Laura Mauri,2Sandro Sonnino2 and Fiamma Ronchetti1
Dipartimento di Chimica, Biochimica e Biotecnologie per la Medicina, Università di Milano
1Via Saldini 50, 20133-Milano, Italy; 2Via Fratelli Cervi 93, 20190- Segrate (Milano), Italy
E-mail:[email protected]
It is widely accepted that glycosphingolipids (GSLs) at the level of the plasma membrane can affect the biological functions of protein molecules, such as cell surface receptors or transporters. The interactions between GSLs and proteins belonging to specific membrane microdomains, called lipid rafts, could be responsible for the modulation of the functional properties of membrane proteins participating in signal transduction. GSL-protein interactions can be investigated by cell photolabelling experiments using radioactive photoactivable GSLs, which yield, when illuminated, a very reactive intermediate that covalently binds to the molecules in the environment, i.e. proteins.1,2
In this context, we have designed a fatty acid probe with two nitrophenylazide photoactivable groups, one at position 2 and the other at the end of the acyl chain. The conjugation of the fatty acid to a radioactive sphingoglycolipid generates a species to be used for photolabelling experiments. In this way, the simultaneous identification of the proteins belonging to both the leaflets of the plasma membrane, the cytoplasmatic and the extracellular one, will be realized.
Herein we describe a general synthetic strategy to obtain not commercially available α,ω-diamino acids, the synthetic precursors of the labelled fatty acids, which we have applied to the synthesis of a C-18 derivative. Furthermore, it will be described the preparation of a photolabelled radioactive GSL as a case study.
1. Aureli M., Prioni S., Mauri L. Loberto N., Casellato R., Ciampa M.G., Chigorno V., Prinetti, A.; Sonnino S. J. Lipid Res. 2010, 51, 798-808
2. Mauri L., Prioni S., Loberto N., Chigorno V., Prinetti A., Sonnino S. Glycoconj. J. 2004, 20, 11-23
Comparative energy and economic performance analysis of an electrochromic window and automated external venetian blind
No full textA virtual test cell representing a portion of an office building was modeled in order to evaluate the energy balance and the economic convenience related to the use, as solar control devices, of a switchable electrochromic glazing system (EG) and of an automated external venetian blind system (VB). Furthermore, results were compared with a so-called base case (BC) of the glazed component, with no exterior solar shading. The virtual test cell is supposed
located in Milan, Italy. The operation of both shading systems was set in order to minimize undesirable solar heat gains during cooling season and to maximize them during heating season and also in order to optimize the daylighting performance without having glare effect on the work plane. The energy balance of the selected systems
was done considering the annual primary energy consumption for heating, cooling, lighting, shading system operation and the glazed systems’ embodied energy annual quota. Finally, a further comparison in terms of economic convenience was done. Simulations were performed using EnergyPlus 7.0 dynamic simulation engine in conjunction with BESTenergy Graphic User Interface
Renovation of an UNESCO heritage settlement in southern Italy: ASHP and BIPV for a “Spread Hotel” project
No full textMany small historical settlements in Mediterranean areas have a great value in terms of architectural and cultural
heritage. Therefore it happens that the socio–economic situation of many of these settlements is backward and
depressed. A succesful way to develop these important environments is to implement tourism, a profitable and
available economical resource. “Spread Hotel” or “Diffuse Hotel” or “Albergo Diffuso” is an innovative concept
which aims to renovate decayed buildings situated in historical locations. New economical inputs are needed to
revitalize these settlements and their social tissue. “Diffuse Hotel” concept is very diffused in Italy due to its rich
historical heritage. The present paper displays a renovation project of a rural historical settlement into a “Spread
Hotel”. The site under analysis is located in Palazzolo Acreide, Sicily, Italy. The settlement strongly needed to be
refurbished in order to provide habitability and to guarantee a proper level of comfort according to italian standards.
The area is also listed in the UNESCO Heritage. The “Diffuse Hotel” at a national level is considered as an affordable
and comfortable concept that enables the travellers to experiance Italy through a tipical, historical and comfortable
hotel. The historical built enviroment preservation is strategic in Italy and can strongly support economical
revitalization. European Community supports the development of “Spread Hotels” projects in order to improve
economical capacity of depressed areas by financing refurbishment programs. In this contest the authors present how
“Palazzolo Acreide” renovation project was done. In particular, the design strategy was to respect the local
characteristics, improve thermal performance and HVAC systems and exploting the on site renewable energy. In fact,
in the Mediterranean areas solar radiation is a incredible resource to provide energy to the buildings
The conformational behaviour of the C-glycosyl analogue of sulfatide studied by NMR in SDS micelles
No full textThe conformational behaviour of sulfatide and its C-glycosyl analogue has been studied by using a combination of J and NOE data assisted by molecular mechanics calculations. There is a major exoanomeric conformation around the phi angle of both molecules with two or three conformers contributing to the equilibrium around psi. The mm3* calculations only provide a qualitative description of the actual population distribution. Despite this geometrical similarity, the quantitative analysis of the NOE intensities at a variety of mixing times indicates that the motion around the pseudoglycosidic linkages of the C-glycosyl analogue is faster than that for the natural compound
Energy and environmental impact of domestic heating in Italy: Evaluation of national NOx emissions
No full textThe domestic heating sector has a high potential in terms of energy savings and environmental impact. In the present study, an analysis has been carried out on the effect of domestic heating on natural gas consumption and pollutants emissions. In particular, among various emission pollutants, the nitrogen oxides (NOx) emissions at national level were analyzed in detail. The work was carried out under a collaborative research project between the Italian Ministry of the Environment and Politecnico di Milano.
For the assessment of the national NOx emissions due to residential heating, an inventory of the domestic boilers stock operating in Italy from 1999 to 2010 was made. As from a technological point of view, the precise data about the real composition of national domestic boilers stock were incomplete and not updated, a methodological procedure was developed in order to reconstruct the national domestic boilers stock based on the available technologies and thermal power. According to this scenario, the technological improvement of national boilers stock in the last decade was evaluated in terms of natural gas saving and reduced NOx emissions
Of cancer and other things : conversations with the Royal Philosopher on pilgrimage to Santiago de Compostella
No full textThis dissertation presents an outline, and one interpretation of, the life of its author, The Reverend Doctor Melvyn John Macarthur. It seeks to do this through both its methodology, which is textual and experiential, and through dialogue with the provocateur, Qoheleth, author of the book of Ecclesiastes. The dialogue component (the ‘Conversations’) reflects the author’s passion to engage with people in conversation and also his love of theatre.
The ‘Conversations’ in the dissertation take place on the Camino Santiago de Compostella (French Way), a long distance, ancient pilgrim route from St Jean Pied de Port in France to Santiago de Compostella in Spain. The dialogue partners are the author of the dissertation and Qoheleth. Qoheleth, the self-proclaimed Royal Philosopher, is a mysterious figure about whom much is conjectured, but little known. Qoheleth has been, and remains, a controversial figure in the Judeo-Christian traditions: considerable numbers of people, whether lay, ordained or scholar, hold that Ecclesiastes should not have been included in the canons. This author holds the view that the work of Qoheleth is among the most thoughtful and unique of the canonical writings. One hope held for this dissertation is that it would be a vehicle whereby I could ‘lean toward’ (Pelias, 2016; 9-11) the person Qoheleth. The motivation for doing this is that his remarkable honesty and depth of thought commends Qoheleth as an ideal provocateur, one who is able to offer a searching critique of the wide and varied life experience of the author, one who it is enticing to lean toward. Ronald Pelias (2016; 12) writes of his use of multiple qualitative methods in the writing of personal narratives. The methodology of this dissertation is, likewise, eclectic, and I would argue, ’necessarily’ so. A human life is complex and mine is no exception. A human life does not readily lend itself, convincingly at least, to understandings from a single discipline. This dissertation draws on material and methods from a variety of disciplines in an endeavour to convey and clarify aspects of the life of the author. The influences in the life of this author are, as mentioned, wide and varied: his professional life in social work, particularly in child protection; his vocational life in ordained ministry and pilgrimage; his more than four decades of participation as a student and researcher in a wide variety of pursuits in the academy; his experience of wilderness for significant periods during his adult lifetime and his last ten years of living with a life threatening cancer (non Hodgkins lymphoma) have all significantly impacted his life. The methodology of the dissertation is built upon these foundations that are termed ‘abiding interests’.
For anyone wishing to have more detail of the author’s life prior to the reading of this dissertation, a brief curriculum vitae is attached as Appendix One.
An appraisal of the author’s account is presented at the conclusion of the ‘Conversations’ with Qoheleth. The appraisal takes the form of commentaries written from the widely differing theological, philosophical and social perspectives of the Reverend Brand, the central character of Henrik Ibsen’s play Brand and the Grand Inquisitor, a prominent figure in Fyodor Dostoevsky’s novel, The Karamazov Brothers. The author’s personal reflections about the pilgrimage to Santiago follow on from and take a full account of, the appraisals of The Reverend Brand and the Grand Inquisitor, in addition to the conversations with Qoheleth
A 2,3-carbamate-bearing allyl galactosamine donor for the synthesis of repeating alfa-(1 4)-linked galactosamine units
No full textThe 1,2-cis-linked 2-amino-2-deoxy sugar structure is found in various oligosaccharides of biological importance. The repeating GalpNAc--(1→4)-GalpNAc unit constitutes for example an essential motif incorporated in a range of oligosaccharides, e.g. the repeating unit of the O-antigen moiety of the lipopolysaccharide from Escherichia Coli O142 or Sphaerotilus natans.[1] Vi antigen is instead a linear homopolymer of -(1→4)-linked N-acetyl galactosaminuronic monomers, with a variable degree of O-acetylation at the C3 position. Vi antigen is a capsular polysaccharide found mainly in Salmonella typhi and Salmonella paratyphi C, two serotypes of Salmonella that are responsible for severe infection in humans.[2]
Although in the past years there has been much progress in carbohydrate chemistry, 1,2-cis-selective glycosylation of gluco- or galactosamines is still a challenge. 2-Azidoglycosyl donors, developed many years ago, are still employed for the synthesis of 2-amino-2-deoxy -glycosides, even if glycosylations suffer of low selectivity. Progress in resolving these issues has been made with the development of donors carrying a 2,3-trans-carbamate group, which has attracted much attention as a stereodirecting protection in glycosylation reactions. The fused carbamate ring proved to be a non-participating group and favors the formation of -glycosides. So far, different studies have demonstrated that 2,3-oxazolidinone protected thioglycosides are highly efficient substrates for the synthesis of -linked glycosides.[3]
Herein we report a new 2,3-oxazolidinone protected galactosamine donor, bearing an allyl group at the anomeric position. The allyl group, in addition to its traditional role as a valuable anomeric protecting group, can also be converted into a good leaving group for glycosylation. Thus, the allyl glycoside is first isomerized to the corresponding prop-1-enyl glycoside, which, after chemoselective activation of the anomeric enol ether moiety with a suitable electrophile in the presence of the glycosyl acceptor, leads to the formation of the disaccharide product.[4] This method has the advantage that prop-1-enyl glycoside can be directly derived from allyl glycoside with a variety of facile and highly effective isomerization methods and immediately subjected to glycosylation.
Herein we describe the synthesis of a galactosamine building block, which has the anomeric position protected by an allyl group, and positions 2 and 3 involved in the formation of an oxazolidinone ring. The proper donor and acceptor to perform a -(1→4) glycosylation have been obtained from this common building block. The new 2,3-oxazolidinone protected allyl galactosamine donor has been subjected to glycosylation reactions to study its reactivity and the stereoselectivity of the process.
1. a) Landersjö, C.; Widmalm, G. Biopolymers 2002, 64,283; b) Takeda, M.; Nakamori, T.; Hatta, M.; Yamada, H.; Koizumi,
J.I. Int. J. Biol. Macromol. 2003, 33, 245
2. a) Daniels, E.M.; Schneerson, R.; Egan, W.M.; Szu, S.C.; Robbins, J.B. Infect. Immun. 1989, 57, 31592; b) Heyns, K.;
Kiessling, G. Carbohydr. Res. 1967, 3, 340
3. See for examples: a) Kerns R.J., Zha C., Benakli K.,. Liang Y.Z, Tetrahedron Lett. 2003, 44, 8069; b) Olsson, J. D. M.;
Eriksson, L.; Lahmann, M.; Oscarson, S. J. Org. Chem: 2008, 73, 7181; c) Yang, L.; Ye, X-S. Carbohydr. Res. 2010, 345,
1713; d) Yang, L.; Zhu, J. ; Zheng, X-J. ; Tai, G. ; Ye, X-S. Chem. Eur. J. 2011, 17, 14518
4. Wang, Y.; Zhang, X.; Wang, P. Org. Biomol. Chem. 2010, 8, 4322 and references herein reported.
We acknowledge MIUR-Italy (PRIN 2008) for financial support
The conformational behaviour of the C-glycosyl analogue of sulfatide studied by NMR in SDS micelles
No full textFrom \u27\u27secret cell\u27\u27 to compostella: Medieval itineararies of \u27Theosis\u27
No full textThe medieval author who sought to faithfully represent spiritual experience was aware that his task was hampered by the very medium in which he worked: language, like the world which it mediated, had been alienated from God through the Fall. As a solution to this problem, he sought to create a sacred space within his text where historical experience could intersect with a sacred intertext, thereby permitting the encounter with God, theosis. By elaborating such textual reliquaries, the author could then claim transcendent authority despite being forced to articulate those claims in fallen language. This dissertation studies these ideas as demonstrated in Augustine\u27s Confessions and two early medieval pilgrimage guides, the Itinerarium Egeriae and the Guide du pelerin de Compostelle, and is divided into 6 chapters. The introduction provides a general overview of medieval strategies for making God accessible, along with a discussion of Scripture as the paradigmatic authority for such an attempt. Chapter 1 discusses Augustine\u27s elaboration of the secret cell , an internal textual reliquary to which man, like the Prodigal Son, returns from exile in the fallen world through the authority of Scripture. Chapter 2 identifies the Itinerarium as a text which seeks to project the experience of the secret cell onto the landscape of the Holy Land, substituting the pilgrim for the exile as the figure authorized by Scripture. Chapter 3 examines the first chapters of the Guide in the light of the Itinerarium and then focuses on the role of Roland and Roncevaux in the pilgrim\u27s search for authority. Chapter 4 demonstrates how the Guide rewrites the material of the first part so as to frame it in terms of the community of saints and, more specifically, in terms of the confessor; it ends by suggesting that the chasse of St. Gilles merits so much attention from the pilgrim because it serves to guarantee his whole project. The conclusion discusses why arriving at Compostella is not necessary for the success of the pilgrimage, and suggests ways in which the itinerary from sacred cell to Compostella might be extended into the later medieval period
I rock glacier come “warm stage refugia”: un modello di studio applicato alle artropodocenosi alpine
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