122,837 research outputs found
Unusual oxygen binding behaviour of a 24-meric crustacean hemocyanin.
No full textHemocyanins from Crustacea usually are found as 1 x 6 or 2 x 6-meric assemblies. An exception is the hemocyanin isolated from thalassinidean shrimps where the main component is a 24-meric structure. Our analysis of oxygen binding data of the thalassinidean shrimp Upogebia pusilla based on a three-state MWC-model revealed that despite the 24-meric structure the functional properties can be described very well based on the hexamer as allosteric unit. In contrast to the hemocyanins from other thalassinidean shrimps the oxygen affinity of hemocyanin from U. pusilla is increased upon addition of L-lactate. A particular feature of this hemocyanin seems to be that L-lactate already enhances oxygen affinity under resting conditions which possibly compensates the rather low intrinsic affinity observed in absence of L-lactate. The fast rate of oxygen dissociation might indicate that in this hemocyanin a higher cooperativity is less important than a fast response of saturation level to changes in oxygen concentration
Meric Michèle — Le mariage névrotique
No full textB H. Meric Michèle — Le mariage névrotique. In: Population, 23ᵉ année, n°5, 1968. p. 946
Unusual oxygen binding behavior of a 24-meric crustacean hemocyanin
No full textHemocyanins from Crustacea usually are found as 1 × 6 or 2 × 6-meric assemblies. An exception is the hemocyanin isolated from thalassinidean shrimps where the main component is a 24-meric structure. Our analysis of oxygen binding data of the thalassinidean shrimp Upogebia pusilla based on a three-state MWC-model revealed that despite the 24-meric structure the functional properties can be described very well based on the hexamer as allosteric unit. In contrast to the hemocyanins from other thalassinidean shrimps the oxygen affinity of hemocyanin from U. pusilla is increased upon addition of l-lactate. A particular feature of this hemocyanin seems to be that l-lactate already enhances oxygen affinity under resting conditions which possibly compensates the rather low intrinsic affinity observed in absence of l-lactate. The fast rate of oxygen dissociation might indicate that in this hemocyanin a higher cooperativity is less important than a fast response of saturation level to changes in oxygen concentration. © 2010 Elsevier Inc. All rights reserved
The molecular heterogeneity of hemocyanin: structural and functional properties of the 4x6-meric protein of Crustacea.
No full textThe structural properties of the hemocyanin isolated from the Mediterranean mud shrimp, Upogebia pusilla (Decapoda: Thalassinidea), were investigated. Our intent was to make use of the U. pusilla case to perform a structural comparison between crustacean and chelicerate 4 x 6-meric hemocyanins. The thalassinidean hemocyanin appears similar in size but different in structural organization compared to the chelicerate 4 x 6-mer. Ultracentrifiage analyses on the purified protein revealed a sedimentation coefficient of 39S, typical of 4 x 6 hemocyanins. Electron micrographs are in agreement with a model in which four 2 x 6-meric building blocks are arranged in a tetrahedron-like quaternary structure and not in the quasi-square-planar orientation characteristic of the chelicerate protein. Size-exclusion chromatography-fast protein chromatography analysis showed elevated instability of the protein in absence of divalent ions or at pH values higher than 8.0. This analysis also shows that the dissociation of the U. pusilla 4 x 6-meric hemocyanin into hexamers occurs without any intermediate 2 x 6-meric state, in contrast with the dissociation profile of the chelicerate protein exhibiting several dissociation intermediates. The oxygen-binding properties of U. pusilla hemocyanin were studied to disclose possible effects by the typical allosteric effectors that modulate the functional properties of crustacean hemocyanin. A marked Bohr and lactate effect, but no significant influence of urate, on the oxygen affinity of U. pusilla hernocyanin were found
LOFTUSIA-TURCICA MERIC AND AVSAR N-SP FROM THE MAASTRICHTIAN OF EASTERN TURKEY (SOUTHEAST ELAZIG)
No full textA new foraminiferal species of Loftusia, Loftusia turcica which is thin, long, fusiform shaped, with sharp-pointed poles and alveolar structure, is described and figured. It is found in shale and argillaceous sandstone of the Middle-Upper Maastrichtian over the Yuksekova complex near the village of Seyhkatil, southeast of Elazig, Eastern Anatolia (Turkey)
R. Genin-Meric, La maxime « locus régit actum ». Nature et fondement
No full textR. Genin-Meric, La maxime « locus régit actum ». Nature et fondement. In: Revue internationale de droit comparé. Vol. 30 N°2, Avril-juin 1978. p. 693
R. Genin-Meric, La maxime « locus régit actum ». Nature et fondement
No full textR. Genin-Meric, La maxime « locus régit actum ». Nature et fondement. In: Revue internationale de droit comparé. Vol. 30 N°2, Avril-juin 1978. p. 693
Rain-flagging of the Envisat altimeter
No full textAs the goals for altimetric measurements become ever more precise, there is concern about the reliable detection and discarding of rain contaminated data. A dual-frequency rain detection technique developed for the Ku- and C-band TOPEX altimeter, is adapted for the Ku- and S-band RA-2 altimeter on Envisat. Of particular concern is the selection of a suitable threshold to minimise the quantity of good data inadvertently discarded
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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