Search results for " Quaternary"

Recombinant functional multidomain hemoglobin from the gastropod Biomphalaria glabrata

2011

The extracellular hemoglobin multimer of the planorbid snail Biomphalaria glabrata, intermediate host of the human parasite Schistosoma mansoni, is presumed to be a 1.44 MDa complex of six 240 kDa polypeptide subunits, arranged as three disulfide-bridged dimers. The complete amino acid sequence of two subunit types (BgHb1 and BgHb2), and the partial sequence of a third type (BgHb3) are known. Each subunit encompasses 13 paralogus heme domains, and N-terminally a smaller plug domain responsible for subunit dimerization. We report here the recombinant expression of different functional fragments of BgHb2 in Escherichia coli, and of the complete functional subunits BgHb1 and BgHb2 in insect ce…

Three-dimensional structure of the anaphase-promoting complex.

2001

The anaphase-promoting complex (APC) is a cell cycle-regulated ubiquitin-protein ligase, composed of at least 11 subunits, that controls progression through mitosis and G1. Using cryo-electron microscopy and angular reconstitution, we have obtained a three-dimensional model of the human APC at a resolution of 24 A. The APC has a complex asymmetric structure 140 A x 140 A x 135 A in size, in which an outer protein wall surrounds a large inner cavity. We discuss the possibility that this cavity represents a reaction chamber in which ubiquitination reactions take place, analogous to the inner cavities formed by other protein machines such as the 26S proteasome and chaperone complexes. This cag…

Heat shock protein 27 is involved in SUMO-2/3 modification of heat shock factor 1 and thereby modulates the transcription factor activity

2009

Heat shock protein 27 (HSP27) accumulates in stressed cells and helps them to survive adverse conditions. We have already shown that HSP27 has a function in the ubiquitination process that is modulated by its oligomerization/phosphorylation status. Here, we show that HSP27 is also involved in protein sumoylation, a ubiquitination-related process. HSP27 increases the number of cell proteins modified by small ubiquitin-like modifier (SUMO)-2/3 but this effect shows some selectivity as it neither affects all proteins nor concerns SUMO-1. Moreover, no such alteration in SUMO-2/3 conjugation is achievable by another HSP, such as HSP70. Heat shock factor 1 (HSF1), a transcription factor responsib…

Incoherent elastic and quasi-elastic neutron scattering investigation of hemoglobin dynamics.

2005

In this work we investigate the dynamic properties of hemoglobin in glycerolD(8)/D(2)O solution using incoherent elastic (ENS) and quasi-elastic (QENS) neutron scattering. Taking advantage of complementary energy resolutions of backscattering spectrometers at ILL (Grenoble), we explore motions in a large space-time window, up to 1 ns and 14 A; moreover, in order to cover the harmonic and anharmonic protein dynamics regimes, the elastic experiments have been performed over the wide temperature interval of 20-300 K. To study the dependence of the measured dynamics upon the protein quaternary structure, both deoxyhemoglobin (in T quaternary conformation) and carbonmonoxyhemoglobin (in R quater…

Quaternary relaxations in sol-gel encapsulated hemoglobin studied via NIR and UV spectroscopy.

2007

In this work, we study the kinetics of the R --T transition in hemoglobin using a combination of near-infrared and near-ultraviolet spectroscopy. We use a sol-gel encapsulation protocol to decelerate the conformational transitions and to avoid spectral perturbations arising from ligand migration and recombination. We monitor two spectroscopic markers: band III in the near-IR, which is a fine probe of the heme pocket conformation, and the tryptophan band in the near-UV, which probes the formation of the Trpbeta37-Aspalpha94 hydrogen bond, characteristic of the T structure, at the critical alpha1beta2 subunit interface. The time evolution of these two bands is monitored after deoxygenation of…

Seismic stratigraphy of the north-westernmost area of the Malta Plateau (Sicily Channel): The Middle Pleistocene-Holocene sedimentation in a tidally …

2022

In this study we present the results of a seismic-stratigraphic analysis of sub-bottom profiles in the north-westernmost area of the Malta Plateau in order to define the depositional mechanisms for the upper Quaternary sequences. During this interval the morphology of the Malta Plateau was characterized by a ramp and bathymetries not exceeding 200 m. Two major unconformities, related to MIS 6 and MIS 2 (the latter corresponding to the Last Glacial Maximum, LGM), characterize the upper Quaternary sequences. The geometries of the recognized seismic units indicate as depositional mechanisms were controlled by subsidence and sea-level fluctuations. In detail, deposits related to the last glacia…

SEA-LEVEL AND CLIMATIC CHANGES DURING THELAST 41,000 YEARS IN THE OUTER SHELF OF THE SOUTHERN TYRRHENIAN SEA: EVIDENCE FROM FORAMINIFERA AND SEISMOST…

2012

HUMAN PEOPLING OF SICILY DURING QUATERNARY

2015

ABSTRACT The early human peopling of Sicily and Western Mediterranean shores is one of the debated topic in the archaeological and anthropological literature over the twentieth century. This discussion involves not only the specific issue of the peopling of the continental island, but fundamentally the reconstruction of human migration routes and dispersals across the Mediterranean area during Early and Middle Pleistocene. Even if the common route of faunal and human movement is considered from North, and relative to the Messina strait crossing, several authors, on the base of archaeological evidences, hypothesized an early peopling and an African provenance through the Sicilian Channel. Th…

The use and beauty of ultra-high-resolution seismic reflection imaging in Late Quaternary marine volcaniclastic settings, Napoli Bay, Italy

2019

A Nápolyi-öbölben felvett ultra nagy felbontású egycsatornás (IKB-Seistec™) reflexiós szeizmikus szelvények korábbi geológiai és geofizikai vizsgálatok eredményeivel együtt kivételes, eddig soha nem látott felbontású szeizmikus leképezését nyújtják a Flegrei-mezők és a Somma-Vezúv felszín alá süllyedt késő-pleisztocén–holocén rétegtani felépí - tésének. A szeizmikus szelvényeken látott geometria és gravitációs magvevővel nyert üledékek adatainak összevetéséből Campania partközeli kontinentális talapzatán számos olyan üledékes és vulkáni szerkezet, valamint hidrotermális jelenség került leképezésre, melyek a legutolsó glaciális maximum (kb. 18 000 év) óta keletkeztek. A Pozzuoli-öbölben mért…

Unità a limiti inconformi utilizzate per la cartografia dei depositi quaternari nei fogli CARG della Sicilia nord-occidentale

2009

Sono riportati i risultati di uno studio sui depositi quaternari del settore settentrionale siciliano compreso tra Trapani e Cefalù. Dettagliati rilevamenti di campagna e analisi stratigrafiche condotti in questa area nell’ambito del Progetto CARG hanno consentito di definire diverse unità a limiti inconformi, del rango di sintema e subsintema, che costituiscono la sintesi regionale degli affioramenti quaternari della Sicilia nord-occidentale. Sono state riconosciute e studiate numerose successioni di terreni di ambiente da continentale a marino costituite da: depositi fluviali, paralici e marini (conglomerati monogenici o poligenici, areniti e/o peliti sciolte o variamente cementate), accu…