Density Anomalies in Crude Oil Blends Reflect Multiple Equilibrium States of Asphaltene Colloidal Aggregates

Density measurements revealed anomalies of nonideality (maxima of excess density) at some compositions in binary blends of light and heavy crude oils from diverse origins. By IR absorption measurements, density anomalies were attributed to increased contents of suspended asphaltene colloidal-sized particles/aggregates in the blends. By comparison with a database of world’s native crude oils, it was concluded that density anomalies may correspond to different equilibrium structural states of asphaltene colloids that occur at several specific asphaltene contents, apparently common for petroleum media of any origin

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

Tissue Specificity of Human Angiotensin I-Converting Enzyme.

Angiotensin-converting enzyme (ACE), which metabolizes many peptides and plays a key role in blood pressure regulation and vascular remodeling, as well as in reproductive functions, is expressed as a type-1 membrane glycoprotein on the surface of endothelial and epithelial cells. ACE also presents as a soluble form in biological fluids, among which seminal fluid being the richest in ACE content - 50-fold more than that in blood.We performed conformational fingerprinting of lung and seminal fluid ACEs using a set of monoclonal antibodies (mAbs) to 17 epitopes of human ACE and determined the effects of potential ACE-binding partners on mAbs binding to these two different ACEs. Patterns of mAbs binding to ACEs from lung and from seminal fluid dramatically differed, which reflects difference in the local conformations of these ACEs, likely due to different patterns of ACE glycosylation in the lung endothelial cells and epithelial cells of epididymis/prostate (source of seminal fluid ACE), confirmed by mass-spectrometry of ACEs tryptic digests.Dramatic differences in the local conformations of seminal fluid and lung ACEs, as well as the effects of ACE-binding partners on mAbs binding to these ACEs, suggest different regulation of ACE functions and shedding from epithelial cells in epididymis and prostate and endothelial cells of lung capillaries. The differences in local conformation of ACE could be the base for the generation of mAbs distingushing tissue-specific ACEs

Observed [M+H]⁺ ions of unglycosylated peptides in the mass spectra of human ACE tryptic digests.

<p>^a Acrylamide adduct on cysteine.</p><p>^b Oxidized methionine.</p><p>^c Contains one or two missed cleavage(s) by trypsin.</p><p>Peptides that contain potential N-glycosylation sites are shown in bold.</p><p>Observed [M+H]⁺ ions of unglycosylated peptides in the mass spectra of human ACE tryptic digests.</p

N-glycosylated peptides and glycan structures found by the GlycoMod tool in ACE from lung and seminal fluid using MS data.

<p>N-glycosylated peptides and glycan structures found by the GlycoMod tool in ACE from lung and seminal fluid using MS data.</p

The structures of N and C domains of ACE with potential glycosylation sites and epitopes for mAbs.

<p>Human N domain structure was based on PDB P2C6N and C domain structure—based on PDB 1O86. The epitopes were marked on the N and C domains according to [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143455#pone.0143455.ref027" target="_blank">27</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143455#pone.0143455.ref031" target="_blank">31</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143455#pone.0143455.ref041" target="_blank">41</a>]. The positions of the epitopes for some mAbs (12 out of 17) are shown by circles on both sides of domain globule. The potential sites of N-glycosylation, 9 on the N domain and 6 on the C domain, are marked by green; Asn494 on the N domain is not seen while Asn1196 is not present in structure of the C domain. The glycosylation sites which might be differently glycosylated in seminal fluid ACE and lung ACE are shown by arrows. Some amino acid residues are shown by numbers according to [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143455#pone.0143455.ref038" target="_blank">38</a>] for orientation.</p