Search results for " Seconda"

Orientation and Dynamics of Peptides in Membranes Calculated from 2H-NMR Data

2009

Solid-state (2)H-NMR is routinely used to determine the alignment of membrane-bound peptides. Here we demonstrate that it can also provide a quantitative measure of the fluctuations around the distinct molecular axes. Using several dynamic models with increasing complexity, we reanalyzed published (2)H-NMR data on two representative alpha-helical peptides: 1), the amphiphilic antimicrobial peptide PGLa, which permeabilizes membranes by going from a monomeric surface-bound to a dimeric tilted state and finally inserting as an oligomeric pore; and 2), the hydrophobic WALP23, which is a typical transmembrane segment, although previous analysis had yielded helix tilt angles much smaller than ex…

Crystal structure of the bifunctional soybean Bowman-Birk inhibitor at 0.28-nm resolution. Structural peculiarities in a folded protein conformation.

1996

The Bowman-Birk inhibitor from soybean is a small protein that contains a binary arrangement of trypsin-reactive and chymotrypsin-reactive subdomains. In this report, the crystal structure of this anticarcinogenic protein has been determined to 0.28-nm resolution by molecular replacement from crystals grown at neutral pH. The crystal structure differs from a previously determined NMR structure [Werner, M. H. & Wemmer, D. E. (1992) Biochemistry 31, 999-1010] in the relative orientation of the two enzyme-insertion loops, in some details of the main chain trace, in the presence of favourable contacts in the trypsin-insertion loop, and in the orientation of several amino acid side chains. The p…

Topology-Dependent Swichability of Peptide Secondary Structures in Bioconjugates with Complex Architectures

2013

Peptide sequences, which exhibit a reversible pH-responsive coil to α-helix secondary structure transition, are conjugated to polymer precursors to yield linear AB and graft ABA peptide-poly(ethylene oxide) conjugates. While the PEO B-block is comparable, the conjugates differ in topologies of the peptide bearing A-blocks. The influences of topology on the structure transitions in the peptide segments are investigated, comparing linear AB-bioconjugates with graft ABA-bioconjugates having multiple peptide segments combined in star or pom-pom topologies.

Formation of covalent di-tyrosine dimers in recombinant α-synuclein

2015

Parkinson's disease is associated with fibril deposition in the diseased brain. Misfolding events of the intrinsically disordered synaptic protein α-synuclein are suggested to lead to the formation of transient oligomeric and cytotoxic species. The etiology of Parkinson's disease is further associated with mitochondrial dysfunction and formation of reactive oxygen species. Oxidative stress causes chemical modification of native α-synuclein, plausibly further influencing misfolding events. Here, we present evidence for the spontaneous formation of covalent di-tyrosine α-synuclein dimers in standard recombinant protein preparations, induced without extrinsic oxidative or nitrative agents. The…

Identification of the membrane penetrating domain of Vibrio cholerae cytolysin as a β-barrel structure

2005

Summary Vibrio cholerae cytolysin (VCC) is an oligomerizing pore-forming toxin that is related to cytolysins of many other Gram-negative organisms. VCC contains six cysteine residues, of which two were found to be present in free sulphydryl form. The positions of two intramolecular disulphide bonds were mapped, and one was shown to be essential for correct folding of protoxin. Mutations were created in which the two free cysteines were deleted, so that single cysteine substitution mutants could be generated for site-specific labelling. Employment of polarity-sensitive fluorophores identified amino acid side-chains that formed part of the pore-forming domain of VCC. The sequence commenced at…

Predicted secondary structure of hydroperoxide lyase from green bell pepper cloned in the yeast Yarrowia lipolytica

2010

International audience; Fatty acid hydroperoxide lyase (HPL) is a member of the cytochrome P450 family acting on fatty acid hydroperoxides in many organisms. The active green bell pepper HPL, cloned and expressed in the yeast Yarrowia lipolytica, was purified by immobilized metal-ion affinity chromatography (IMAC) in the presence of 2% of Triton X-100R. The secondary structure prediction by bioinformatics servers of HPL was realized by ANTHEPROT software, using the GOR, DPM and Predator methods. The theoretical results which are average values obtained from three different calculation methods showed 33% α-helix, 18% β-sheet, 7% turn and 42% coil. On the other hand, the secondary structure a…

Conformation of dehydropentapeptides containing four achiral amino acid residues - controlling the role of L-valine.

2014

Structural studies of pentapeptides containing an achiral block, built from two dehydroamino acid residues (ΔZPhe and ΔAla) and two glycines, as well as one chiral L-Val residue were performed using NMR spectroscopy. The key role of the L-Val residue in the generation of the secondary structure of peptides is discussed. The obtained results suggest that the strongest influence on the conformation of peptides arises from a valine residue inserted at the C-terminal position. The most ordered conformation was found for peptide Boc-Gly-ΔAla-Gly-ΔZPhe-Val-OMe (3), which adopts a right-handed helical conformation.

Chronic myeloid leukemia as second malignancy; a retrospective multicentrico study

2009

Prevenire l’insuccesso scolastico nella scuola secondaria di primo grado: scuola e territorio dialogano

2017

Con il lavoro di co-progettazione per la promozione di una rete integrata tra soggetti pubblici e privati attraverso lo sviluppo di una metodologia di sistema, l’ideazione e realizzazione di strumenti di supporto, è stato offerto un contributo per il contrasto del fenomeno della dispersione scolastica e per la prevenzione del rischio di marginalità sociale negli adolescenti di Palermo. Il progetto ha coinvolto 172 studenti, 171 genitori e 29 docenti di tre scuole secondarie di primo grado, 10 operatori del terzo settore del territorio del Comune di Palermo. Si è partiti dal presupposto che per favorire la dimensione orientativa della scuola media fosse necessario incentivare il dialogo tra …

Expressing perception in parallel ways. Sentential Small Clauses in German and Romance

2021

This chapter compares Pseudo-relatives (‘PRs’), a construction found in most Romance languages, with ‘Subject-wieclauses’ (‘SWs’), a German construction in which the subject of an embedded wie-clause precedes the complementizer wie (‘how’; e.g. Ich sah Maria, wie sie sang, lit. “I saw Mary, how she sung”, i.e. ‘I saw Mary singing’). We show that both constructions mainly occur with perception verbs, and that they have a very similar syntactic behaviour; e.g., they can be coordinated with adjectival or prepositional small clauses and have anaphoric tense. Furthermore, they both have a clausal nature but can modify a DP. We thus propose to extend Casalicchio’s (2016) analysis of PRs to SWs: t…