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41.
Hans Peter Sørensen Lone Søvad Madsen Jørgen Petersen Jesper Tapdrup Andersen Anne Maria Hansen Hans Christian Beck 《Applied biochemistry and biotechnology》2010,160(6):1573-1584
Extracts from different higher plants were screened for the ability to inhibit the growth of Penicillium roqueforti, a major contaminating species in industrial food processing. Oat (Avena sativa) seed extracts exhibited a high degree of antifungal activity and could be used directly on rye bread to prevent the formation
of P. roqueforti colonies. Proteins in the oat seed extracts were fractionated by column chromatography and proteins in fractions containing
antifungal activity were identified by liquid chromatography–tandem mass spectrometry (LC-MS/MS) and database searches. Identified
antifungal candidates included thaumatin-like proteins, 1,3-beta-glucanase, permatin precursor, pathogenesis-related protein
type 1, and chitinases of class I and II. Class I chitinase could be specifically removed from the extracts and was found
to be indispensable for 50% of the P. roqueforti inhibiting activity. The purified class I chitinase has a molecular weight of approximately 34 kDa, optimal chitinase activity
at pH 7, and exists as at least two basic isoforms (pI values of 7.6 and 8.0). Partial sequencing of the class I chitinase
isoforms by LC-MS/MS revealed a primary structure with high similarity to class I chitinases of wheat (Triticum aestivum), barley (Hordeum vulgare), and rye (Secale cereale). Oat, wheat, barley, and rye seed extracts were compared with respect to the abundance of the class I chitinase and decrease
in antifungal activity when class I chitinase is removed. We found that the oat seed class I chitinase is at least ten times
more abundant than the wheat, barley, and rye homologs and that oat seed extracts are highly active toward P. roqueforti as opposed to extracts of other cereal seeds. 相似文献
42.
Maximilian Franta Johannes Gramüller Philipp Dullinger Simon Kaltenberger Prof. Dr. Dominik Horinek Prof. Dr. Ruth M. Gschwind 《Angewandte Chemie (International ed. in English)》2023,62(27):e202301183
Chiral phosphoric acids (CPA) have become a privileged catalyst type in organocatalysis, but the selection of the optimum catalyst is still challenging. So far hidden competing reaction pathways may limit the maximum stereoselectivities and the potential of prediction models. In CPA-catalyzed transfer hydrogenation of imines, we identified for many systems two reaction pathways with inverse stereoselectivity, featuring as active catalyst either one CPA or a hydrogen bond bridged dimer. NMR measurements and DFT calculations revealed the dimeric intermediate and a stronger substrate activation via cooperativity. Both pathways are separable: Low temperatures and high catalysts loadings favor the dimeric pathway (ee up to −98 %), while low temperatures with reduced catalyst loading favor the monomeric pathway and give significantly enhanced ee (92–99 % ee; prior 68–86 % at higher temperatures). Thus, a broad impact is expected on CPA catalysis regarding reaction optimization and prediction. 相似文献
43.
Two physiologically important forms of vitamin D exist: vitamin D2 and vitamin D3, which by liver based hydroxylase enzymes are converted to 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3, respectively. These hydroxylated metabolites of vitamin D are measured in plasma to assess the vitamin D status of animals and humans. Therefore cheap and reliable analytical methods are very much in demand in nutritional and physiological research. After saponification and extraction of plasma or serum samples the current method uses reverse phase high performance liquid chromatography on a C30 column and with UV detection at 265 nm for quantifying vitamin D2, vitamin D3, 25-hydroxyvitamin D2, and 25-hydroxyvitamin D3. The method proved versatile with respect to plasma lipid content, sample amount, and plasma concentration of the vitamin D metabolites as it was tested using plasma from six different species: cattle, pigs, poultry, mink, horses, and humans. In cattle plasma recoveries were between 86.6 and 101.0%, within day error between 0.9 and 5.9%, and between day error between 0.2 and 1.7%. However, depending on species and sample amount error percentages varied. When running the method on standard reference material® 972 “Vitamin D in human serum” from the National Institute of Standards and Technology (NIST) (Gaithersburg, USA) the results for 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 concentrations were within the boundaries provided by NIST, reflected by Z-scores between 0.1 and 0.9. 相似文献
44.
45.
Jesper Kristiansen Jytte Molin Christensen Lone Lillemark Svend Aage Linde Jill Merry Bente Nyeland Ole Petersen 《Fresenius' Journal of Analytical Chemistry》1995,352(1-2):157-162
A network between 6 Danish laboratories with experience in quality assurance and quality control has been established with the aim of supporting the use and production of high-quality certified reference materials in Denmark. One of the tasks of the network was to develop a PC-program for computer-aided quality assurance and certification of reference materials produced by the network laboratories. This paper describes the design and features of the DANREF PC-program and shows examples of computer-aided evaluation of selected studies on reference materials. The program provides the network laboratories with the possibility to carry out harmonized statistical evaluation and documentation of homogeneity, stability and intercomparison studies in accordance with international guidelines and standards, e.g. ISO guide 35. 相似文献
46.
Christian Gram 《BIT Numerical Mathematics》1964,4(3):156-161
Two representations of zero in floating-point arithmetic are considered in relation to a summation with correction for rounding errors. The common representation with exponent zero is shown in this case to be better than the academic representation where the exponent depends on the history of the zero. 相似文献
47.
Lone B Madsen Bo Thomsen Knud Larsen Christian Bendixen Ida E Holm Merete Fredholm Arne L Jørgensen Anders L Nielsen 《BMC neuroscience》2007,8(1):72
Background
The transmembrane presenilin (PSEN) proteins, PSEN1 and PSEN2, have been proposed to be the catalytic components of the γ-secretase protein complex, which is an intramembranous multimeric protease involved in development, cell regulatory processes, and neurodegeneration in Alzheimer's disease. Here we describe the sequencing, chromosomal mapping, and polymorphism analysis of PSEN1 and PSEN2 in the domestic pig (Sus scrofa domesticus). 相似文献48.
Cross-sections for doubly radiative thermal neutron capture on 2H, 3He, 16O and208Pb are calculated to be 21, 1200, 41 and 50 nb, corresponding to branching ratios of σ(n, γγ)/σ(n, γ) = 4.0 × 10?5, ~ × 10?2, 2.2 × 10?4 and 1.0 × 10?4, respectively. 相似文献
49.
A certain class of results about the different representations of Oblique projectors is present in the literature. These results represent Oblique projectors as the functions of orthogonal projectors with given onto and along spaces. But these results are valid under the restriction that the functions of orthogonal projectors involved are invertible. In this paper we extend and generalize these results. The extension lies in making a transition from Euclidean space to Minkowski space M and the generalization is obtain by voiding the invertibility condition and use of the Minkowski inverse. Furthermore, the nobility lies in utilizing the m-projectors instead of the regular orthogonal projectors. 相似文献
50.
G. W. Monier-Williams W. C. Vosburgh F. W. Zerban H. Herissey A. Chalmata W. S. Iljin C. Lundsgaard Chr N. J. Gram S. A. Holbøll E. Rud A. Schachkeldian L. Ekkert E. W. Rice G. L. Bidwell W. F. Sterling J. Fiehe und W. Kodatzki 《Fresenius' Journal of Analytical Chemistry》1930,81(5-7):262-268
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