1,720,974 research outputs found
The role of (4R, 2S) hydroxyl-proline in the molecular and supramolecular structure of elastin model peptides
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Molecular and supramolecular structure of elastin model peptides containing (2S,4R)-4- hydroxy-proline
No full textA two-year database of BC measurements at the biggest European crude oil pre-treatment plant: a comparison with organic gaseous compounds and PM10 loading
No full textA two-year data-set of black carbon (BC) measurements collected in a site in South Italy close to the biggest European pre-treatment plant (COVA) of crude oil has been studied. The area named Val d'Agri, in Basilicata Region, is also crossed by the main road SS598. Data have been collected by using a 7 wavelength aethalometer allowing the measurement of equivalent black carbon (EBC) content, the estimation of Ångström absorption exponent (AAE), and the detection of organic fraction presence through UVPM (UV-absorbing particulate matter) quantity. Data have been analyzed to distinguish seasonal behaviors and characteristics of carbonaceous aerosols. No evident seasonal patterns have been observed for EBC concentrations with a mean value of 643±415ng/m3 and a large short-term variability, with frequent periods (few days or few weeks) of intense emissions associated to COVA activities. EBC averaged daily trends show two main peaks, one in the morning and one in the evening suggesting a contribution of traffic as a background source of BC on a long-term basis, due to the SS598 passing near the measurement site. On a four month period in 2013, a comparison with co-located PM10 concentrations data has been carried out showing a relevant contribution of EBC to the total particle loading at the site. Unlike EBC, AAE shows higher values (maximum value 1.3±0.3) during cold periods and lower values (minimum value 0.9±0.2) in the warmer seasons. Anti-correlation has been observed when comparing AAE with both solar radiation and temperature. In addition, enhanced values during night time for AAE average daily patterns have been observed despite the seasons, suggesting relevant additional sources of organic carbon other than traffic related to COVA emissions during the year. Moreover a good agreement, on a short-term basis, has been found among UVPM, benzene, toluene
On enhancers and inhibitors of elastin-derived amyloidogenesis
No full textThe main aim of this study is to better understand the self-aggregation mechanism of amyloid-like elastin-derived fibers in order to design and produce new powerful drugs that will inhibit the onset of 'amyloidosis'.Atomic force microscopy (AFM), Congo Red birefringence assay and Thioflavin T fluorescence measurements were used to demonstrate the amyloid-like behavior of some fragments of elastin protein (exon 30 [EX30] and exon 28 [EX28]). Turbidimetry on apparent absorbance technique was used to investigate the effect either of enhancers or of inhibitors on the amyloidogenic elastin-like peptides. Circular-dichroism spectroscopy was used to study the secondary structures of the peptides.We used Congo Red birefringence assay, Thioflavin T fluorescence measurements and AFM measurements that are used commonly to demonstrate the formation of amyloids. The elastin fibrillogenesis is amyloid-like. Then, the elastin amyloidogenesis is inhibited by particular pentapeptides.We have reported herein that the fibrillogenesis of elastin-derived EX28 and EX30 polypeptides is facilitated significantly by the effect of sodium taurocholate bile salt and is inhibited by a classical inhibitor of Abeta-amyloid peptide, such as KLVFF, as well as by novel inhibitors, designed by us on the basis of some elastin sequences
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Molecular and supramolecular studies on polyglycine and poly-L-proline
No full textElastin is a cross-linked protein, whose soluble precursor is tropoelastin, responsible for resilience and elastic recoil in vertebrate tissues. Glycine and proline are among the most repeated amino acids in tropoelastin primary structure, the high flexible glycine being present 222 times and the more constrained proline being present 96 times. In order to deeper investigate the role of glycine and proline residues in elastin, we studied the molecular and supramolecular structures of polyglycine and poly-l-proline homopolypeptides as significant sequences for the protein. As a matter of fact, up to now, if few conformational studies are accessible only for poly-l-proline homopolypeptide in solution and for polyglycine homopolypeptide in the solid state, limited supramolecular studies are available for both homopolypeptides. Given the self-aggregation properties of these homopolypeptides, we investigated the aggregation mechanism by turbidimetry measurements together with Congo red birefringence assay, ThT fluorescence spectroscopy, and atomic force microscopy and transmission electron microscopy studies. At molecular level, we show the dominance of the cross-β structure for polyglycine fibrils while for poly-l-proline aggregates PPII conformation prevails. At supramolecular level, the results show that polyglycine is able to self-aggregate into amyloid-like fibres while poly-l-proline aggregates by following a specific pathway ranging from protofibrils to fibrils. These findings suggest that the self-aggregation properties of elastin are influenced by tropoelastin primary structure thus explaining why glycine-rich elastin-derived polypeptide sequences are amyloidogenic (Gly-effect) while proline-rich elastin-derived polypeptide sequences (Pro-effect) are able to coacervate. © The Royal Society of Chemistry 2011
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