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Using the imidate procedure, 2,3,4,6-tetra-O-benzyl-1-O-(N-methylacetimidoyl)-β-d-galactopyranose was condensed with various monosaccharides to provide, in good yield and with high stereoselectivity, α-linked disaccharides. 相似文献
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Pierre Bongrand Gilles Bouvenot Robert Bartolin J Jeanne Tatossian Bernard Bruguerolle 《Chronobiology international》1988,5(1):81-83
Eleven male subjects were investigated to detect a possible circadian rhythm of the polymorphonuclear phagocytosis. Both cell activity and serum opsonins were studied for numerical detection of granulocytes having ingested at least one particle and for the mean number of ingested particles per cell. No significant temporal differences (ANOVA and cosinor) were found. 相似文献
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Dieter Schouppe Pierre Rougé Yi Lasanajak Annick Barre David F. Smith Paul Proost Els J. M. Van Damme 《Glycoconjugate journal》2010,27(6):613-623
At present the three-dimensional structure of the tobacco lectin, further referred to as Nictaba, and its carbohydrate-binding
site are unresolved. In this paper, we propose a three-dimensional model for the Nictaba domain based on the homology between
Nictaba and the carbohydrate-binding module 22 of Clostridium thermocellum Xyn10B. The suggested model nicely fits with results from circular dichroism experiments, indicating that Nictaba consists
mainly of β-sheet. In addition, the previously identified nuclear localization signal is located at the top of the protein
as a part of a protruding loop. Judging from this model and sequence alignments with closely related proteins, conserved glutamic
acid and tryptophan residues in the Nictaba sequence were selected for mutational analysis. The mutant DNA sequences as well
as the original Nictaba sequence have been expressed in Pichia pastoris and the recombinant proteins were purified from the culture medium. Subsequently, the recombinant proteins were characterized
and their carbohydrate binding properties analyzed with glycan array technology. It was shown that mutation of glutamic acid
residues in the C-terminal half of the protein did not alter the carbohydrate-binding activity of the lectin. In contrast,
mutation of tryptophan residues in the N-terminal half of the Nictaba domain resulted in a complete loss of carbohydrate binding
activity. These results suggest that tryptophan residues play an important role in the carbohydrate binding site of Nictaba. 相似文献
48.
Photo-oxidative damage in the ripening tomato fruit: Protective role of superoxide dismutase 总被引:2,自引:0,他引:2
Factors relating to photo-oxidative damage in tomatoes were investigated during maturation of the fruit and upon induction of sunscald. Superoxide dismutase (SOD) activity passed through a minimum at the mature-green and breaker stages of ripening and availability of zinc and copper did not appear to be a limiting factor in the synthesis of the enzyme. Iron levels were maximal and total carotenoid concentrations were lowest during the same mature-green and breaker stages of maturation, while chlorophyll was starting to decrease but was still present in large amounts. Peroxidase activity decreased steadily during ripening. Artificial induction of tolerance to photodynamic damage by controlled heat treatment was accompanied by an increase in SOD activity, while carotenoid levels and peroxidase activity did not change. These findings support the thesis that the previously reported susceptibility of tomatoes to photodynamic damage, i.e. sunscald, during the mature-green and breaker stages of maturation is related to enhanced formation of superoxide ions, at a time when chloroplast structure begins to break down. SOD, by scavenging the superoxide, appears to supplement the protective action of carotenoids against photo-oxidative injury. 相似文献
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Barbara Tillmann Pierre Jolic?ur Masami Ishihara Nathalie Gosselin Olivier Bertrand Yves Rossetti Isabelle Peretz 《PloS one》2010,5(4)
Congenital amusia is a neurogenetic disorder of music processing that is currently ascribed to a deficit in pitch processing. A recent study challenges this view and claims the disorder might arise as a consequence of a general spatial-processing deficit. Here, we assessed spatial processing abilities in two independent samples of individuals with congenital amusia by using line bisection tasks (Experiment 1) and a mental rotation task (Experiment 2). Both amusics and controls showed the classical spatial effects on bisection performance and on mental rotation performance, and amusics and controls did not differ from each other. These results indicate that the neurocognitive impairment of congenital amusia does not affect the processing of space. 相似文献