Search results for "Quaternary"

Subunit organization of the abalone Haliotis tuberculata hemocyanin type 2 (HtH2), and the cDNA sequence encoding its functional units d, e, f, g and…

1999

We have developed a HPLC procedure to isolate the two different hemocyanin types (HtH1 and HtH2) of the European abalone Haliotis tuberculata. On the basis of limited proteolytic cleavage, two-dimensional immunoelectrophoresis, PAGE, N-terminal protein sequencing and cDNA sequencing, we have identified eight different 40-60-kDa functional units (FUs) in HtH2, termed HtH2-a to HtH2-h, and determined their linear arrangement within the elongated 400-kDa subunit. From a Haliotis cDNA library, we have isolated and sequenced a cDNA clone which encodes the five C-terminal FUs d, e, f, g and h of HtH2. As shown by multiple sequence alignments, defg of HtH2 correspond structurally to defg from Octo…

9 Å cryo-EM structure and molecular model of a gastropod hemocyanin didecamer (KLH1) reveals the architecture of the asymmetric collar

2008

Hemocyanins are blue copper proteins that transport oxygen in the hemolymph of many arthropods and molluscs. Molluscan hemocyanins are decamers, didecamers or multidecamers of a 350–400 kDa polypeptide subunit that is subdivided into seven or eight different functional units (FUs, each with a single copper active site). The quaternary structure is a semi-hollow cylinder consisting of a wall and a collar. Recently, we published a 9 A cryo-EM structure and molecular model of a cephalopod hemocyanin decamer (NpH, from Nautilus pompilius) that answered many hitherto unsolved questions concerning the quaternary structure of molluscan hemocyanin. Notably, it revealed the twisted pathway of the 10…

STOP 6: Morphology, internal structure and texture of inland dunes at the Smilškalni site, Middle Gauja Lowland

2014

The arid–humid transition in the Sahara and the Sahel during the last deglaciation

1990

At the time of the Last Glacial Maximum, the Sahara and Sahel regions of North Africa were extremely dry. New records of rainfall show that during the subsequent deglaciation, the transition from arid to humid conditions in these regions occurred synchronously in two main steps. Comparison with other records of palaeoclimate in Europe and the North Atlantic Ocean shows that certain common factors controlled changes in ocean and atmosphere dynamics during the deglaciation.

Waterless Cleaning Compositions with Disinfection Properties: Efficacy and Environmental Aspects / Bezûdens Tîrîðanas Lîdzekïi Ar Dezinficçjoðo Iedar…

2015

Abstract The microbial ecology of different indoor environments determines the human microbiome. Hence, cleaning and disinfection of indoor environments like hospitals, apartments, automobiles, etc. are of great importance. Nonaqueous surface cleaning preparations (SCPs) are often used for this purpose. A cleaning composition may contain the following compounds: primary surfactant, cosurfactant, solvent, cosolvent, organotropic (organic solubilizing) agent, hydrotropic (water solubilising) agent, water and salts, and special additives. In this paper, the efficacy of complex preparations is discussed, focusing on the chemical composition and testing methods. Particular attention is paid to q…

Optical characterization of YCa4O(BO3)3 and Nd:YCa4O(BO3)3 crystals

2007

International audience; We report a complete optical characterization of YCa4O(BO3)3 and Nd:YCa4O(BO3)3 crystals. We studied the relative orientation between the dielectric and the crystallographic frames as a function of the wavelength and performed accurate phase-matching angles measurements for second harmonic generation, using a single crystal cut as a sphere. We also recorded polarized luminescence spectra of Nd:YCOB along the principal axes of the dielectric frame. For both crystals, we measured the gray-tracking and the thermo-optic properties as a function of temperature and wavelength using oriented slabs. Finally, we measured all their dielectric and electro-optic coefficients, as…

Caki-1 cells as a model system for the interaction of renally secreted drugs with OCT3.

2008

<i>Background/Aims:</i> Organic cation transporters (OCT) in the proximal tubules (PTs) participate in the renal secretion of several therapeutic agents. The exact role of OCT3 in renal secretion remains undetermined, partially due to the lack of an appropriate in vitro model system. The current work introduces the PT representative cell line, Caki-1, as a model system for studying the involvement of OCT3 in renal secretion. <i>Methods:</i> Caki-1 cells were characterized for OCT3 expression via real-time RT-PCR and immunocytochemical staining techniques. Uptake kinetics of OCT3 in Caki-1 cells was determined using prototypical substrates and inhibitors. Inhibition o…

Synthesis of alkaloids by Stevens rearrangement of nitrile-stabilized ammonium ylides: (±)-laudanosine, (±)-laudanidine, (±)-armepavine, (±)-7-methox…

2013

The Stevens rearrangement of nitrile-stabilized ammonium ylides in conjunction with the reductive removal of the nitrile function permits the facile construction of α-branched amines from α-aminonitriles. We employed this reaction sequence for the preparation of (±)-laudanosine, (±)-laudanidine and (±)-armepavine, (±)-7-methoxycryptopleurine, and (±)-xylopinine from two closely related and readily accessible bicyclic α-aminonitriles. The final products were obtained in high to almost quantitative yields (71–98%) from the quaternary ammonium salts obtained by N-alkylation of these starting materials.

Mutual Climatic Range Methods for Quaternary Ostracods

2012

Abstract The development of Mutual Climatic Range (MCR) methods for ostracods has included the estimation of marine bottom-water palaeotemperatures, but it has focused mainly on the use of non-marine ostracods to infer past air temperatures. The Delorme analogue MCR method, using only those components of a fossil assemblage that co-exist today, has yielded mean annual air temperature and annual precipitation estimates for North American Quaternary sites. The Mutual Ostracod Temperature Range (MOTR) non-analogue MCR method utilises all species in a fossil assemblage; calibrations based on a European database have been applied to the estimation of mean July and January air temperatures for En…

Organocatalytic Enantioselective Alkylation of Pyrazol-3-ones with Isatin-Derived Ketimines: Stereocontrolled Construction of Vicinal Tetrasubstitute…

2016

A quinine-derived thiourea catalysed the enantioselective addition of 4-substituted pyrazolones to isatin-derived ketimines, providing a variety of aminooxindole-pyrazolone adducts containing congested vicinal tetrasubstituted stereocentres with excellent outcomes (up to 98% yield, >20:1 dr and 98% ee).