1,354,295 research outputs found
Electrospray ionization ion trap multiple-stage mass spectrometric fragmentation pathways of leucine and isoleucine: an ab initio computational study
No full textWe recently demonstrated the possibility to distinguish between leucine and isoleucine in several tryptic peptides by means of consecutive tandem mass steps (Armirotti et al. J. Am. Soc. Mass Spectrom. 2007; 18: 57), exploiting a gas-phase rearrangement of the immonium ion of Ile. In the
present paper we explore the tandem mass spectrometric behaviour of the two amino acids. We propose a plausible structure for the diagnostic m/z 69 ion of Ile, that was reported for the first time in 1996 (Hulst and Kientz J. Mass. Spectrom. 1996; 31: 1188), and we explain why its formation is favoured with respect to Leu. Our conclusions are supported by ab initio quantum chemistry calcultations and isotope-labelled standards experiments
I sectilia pavimentali delle insulae 38 e 39 di Augusta Praetoria (Aosta)
No full textL’Associazione Italiana per lo Studio e la Conservazione del Mosaico (AISCOM) si è costituita a Roma l’11 ottobre 1990 allo scopo di sostenere in Italia i fini istituzionali del corrispondente organismo internazionale (AIEMA), collocandosi accanto ad altre analoghe associazioni nazionali già costituite in Francia, Inghilterra, Spagna, Tunisia, Nord America.
La divulgazione dei fini istituzionali e lo sviluppo stesso dell’AISCOM si basano sull’apertura dell’Associazione al pubblico degli studiosi e di tutti coloro che, in modo diverso, svolgono attività di ricerca e conservazione nel settore del mosaico e dei pavimenti antichi, soprattutto in ambito nazionale
Achievements and perspectives of top-down proteomics
No full textOver the last years, top-down (TD) MS has gained a remarkable space in proteomics, rapidly trespassing the limit between a promising approach and a solid, established technique. Several research groups worldwide have implemented TD analysis in their routine work on proteomics, deriving structural information on proteins with the level of accuracy that is impossible to achieve with classical bottom-up approaches. Complete maps of PTMs and assessment of single aminoacid polymorphisms are only a few of the results that can be obtained with this technique. Despite some existing technical and economical limitations, TD analysis is at present the most powerful instrument for MS-based proteomics and its implementation in routine workflow is a rapidly approaching turning point in proteomics. In this review article, the state-of-the-art of TD approach is described along with its major advantages and drawbacks and the most recent trends in TD analysis are discussed. References for all the covered topics are reported in the text, with the aim to support both newcomers and mass spectrometrists already introduced to TD proteomics
L’Area sacra del Foro di Augusta Praetoria (Aosta, Italia). Modelli architettonici e materiali costruttivi
No full textAugusta Praetoria Salassorum was founded in 25 a.C. by the confluence of two alpine pass viae, after the definitive conquest of the
Alpes Graiae and Poeninae region; since the first phase of its urbanization, it was provided with a monumental Forum. An intensive
campaign of archaeological investigations has focused on the sacred area, a terraced temenos with two twin temples, maybe dedicated to
the imperial cult. Tuscan, Ionic, and Corinthian capitals both in local travertine and conglomerate, recently unearthed, reveal a mixed
decoration belonging to the original building complex. Such simultaneous presence of different architectural orders, applied in a building
context derived from late Republican terraced sanctuaries, provides political ideology with a strong visual power, strengthening the deep
Romanization process in the area. Moreover, an impressive amount of imported marbles from the Forum buildings (slabs, moulded
frames, fragments of monolithic shafts) shows a huge building programme, which lasts up to the mid-Imperial period.
Augusta Praetoria Salassorum, fondata nel 25 a.C. alla confluenza di due corridoi di attraversamento alpino, al culmine del processo
di conquista di Alpes Graiae e Poeninae, si dota fin dalle origini di un imponente complesso forense. Una vasta campagna di indagini
archeologiche ha interessato l’area sacra, temenos terrazzato con due templi gemelli forse destinati al culto imperiale. Capitelli
tuscanici, ionici e corinzi in travertino locale e conglomerato, recuperati negli scavi, rivelano una decorazione architettonica mista
pertinente all’impianto originario: una compresenza di ordini che, in un’area sacra figlia dei complessi terrazzati tardo-repubblicani,
conferisce potenza visiva al radicamento ideologico e materiale di una romanizzazione energica. Inoltre, un’impressionante quantità di
marmi d’importazione (lastre, partiture orizzontali, frammenti di fusti monolitici), provenienti dagli edifici forensi, rivela programmi
monumentalizzanti che si protraggono almeno fino alla media età imperiale
How to Discriminate Between Leucine and Isoleucine by Low Energy ESI-TRAP MSn
No full textIn peptide sequencing experiments involving a single step tandem mass acquisition, leucine and isoleucine are indistinguishable because both are characterized by a 113 Da mass difference from the other peptide fragments in the MS2 spectrum. In this work, we propose a new method to distinguish between these two amino acids in consecutive MSn experiments, exploiting a gas-phase fragmentation of isoleucine that leads to a diagnostic 69 Da ion. We used this method to assess the Leu/Ile residues of several synthetic peptides. The procedure was then tested on a tryptic digest of myoglobin, assigning the correct amino acid in the majority of the peptides. This work was performed with an old and low-resolution instrument, thus demonstrating that our method is suitable for a wide number of ion trap mass spectrometers, not necessarily expensive or up-to-date
Top-down proteomics with a quadrupole time-of-flight mass spectrometer and collision-induced dissociation.
No full textSigle iscritte su elementi architettonici dalle «Terme del Foro» di Augusta Praetoria (Aosta, Italia): un catalogo preliminare
No full textDuring almost one century of excavations at the Terme del Foro of Augusta Praetoria, archaeologists found thousands of artifacts, proofs of the roman building’s life and his transformations. Hundreds of architectural fragments, both structural and decorative, stand out among these items. Many slabs and moulded frames made of Bardiglio (a local lithic type, especially used for ornamental purposes) and of white and veined marbles, are marked by symbols engraved on the displayed surfaces: comparison with similar contexts suggests the hypothesis of signs functional to maintenance activities
La XIV campagna di scavo, in Nora, area E. Le campagne 2003-2004
No full textrelazione degli scavi 2003-2004 a Nor
Monitoring Myelin Lipid Composition and the Structure of Myelinated Fibers Reveals a Maturation Delay in CMT1A
No full textFindings accumulated over time show that neurophysiological, neuropathological, and molecular alterations are present in CMT1A and support the dysmyelinating rather than demyelinating nature of this neuropathy. Moreover, uniform slowing of nerve conduction velocity is already manifest in CMT1A children and does not improve throughout their life. This evidence and our previous studies displaying aberrant myelin composition and structure in adult CMT1A rats prompt us to hypothesize a myelin and axon developmental defect in the CMT1A peripheral nervous system. Peripheral myelination begins during the early stages of development in mammals and, during this process, chemical and structural features of myelinated fibers (MFs) evolve towards a mature phenotype; deficiencies within this self-modulating circuit can cause its blockage. Therefore, to shed light on pathophysiological mechanisms that occur during development, and to investigate the relationship among axonal, myelin, and lipidome deficiencies in CMT1A, we extensively analyzed the evolution of both myelin lipid profile and MF structure in WT and CMT1A rats. Lipidomic analysis revealed a delayed maturation of CMT1A myelin already detectable at P10 characterized by a deprivation of sphingolipid species such as hexosylceramides and long-chain sphingomyelins, whose concentration physiologically increases in WT, and an increase in lipids typical of unspecialized plasma membranes, including phosphatidylcholines and phosphatidylethanolamines. Consistently, advanced morphometric analysis on more than 130,000 MFs revealed a delay in the evolution of CMT1A axon and myelin geometric parameters, appearing concomitantly with lipid impairment. We here demonstrate that, during normal development, MFs undergo a continuous maturation process in both chemical composition and physical structure, but these processes are delayed in CMT1A
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