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21.
Isabella Di Lernia Alessandra Morana Antonio Ottombrino Stefania Fusco Mosè Rossi M. De Rosa 《Extremophiles : life under extreme conditions》1998,2(4):409-416
Enzymes that convert starch and dextrins to α,α-trehalose and glucose were found in cell homogenates of the hyperthermophilic
acidophilic archaeon Sulfolobus shibatae DMS 5389. Three enzymes were purified and characterized. The first, the S. shibatae trehalosyl dextrin-forming enzyme (SsTDFE), transformed starch and dextrins to the corresponding trehalosyl derivatives with
an intramolecular transglycosylation process that converted the glucosidic linkage at the reducing end from α-1,4 to α-1,1.
The second, the S. shibatae trehalose-forming enzyme (SsTFE), hydrolyzed the α-1,4 linkage adjacent to the α-1,1 bond of trehalosyl dextrins, forming
trehalose and lower molecular weight dextrins. These two enzymes had molecular masses of 80 kDa and 65 kDa, respectively,
and showed the highest activities at pH 4.5. The apparent optimal temperature for activity was 70°C for SsTDFE and 85°C for
SsTFE. The third enzyme identified was an α-glycosidase (SsαGly), which catalyzed the hydrolysis of the α-1,4 glucosidic linkages
in starch and dextrins, releasing glucose in a stepwise manner from the nonreducing end of the polysaccharide chain. The enzyme
had a molecular mass of 313 kDa and showed the highest activity at pH 5.5 and at 85°C.
Received: October 29, 1997 / Accepted: April 29, 1998 相似文献
22.
Giuliano Delle Monache Franco Delle Monache Josè Becerra Mario Silva Francesco Menichini 《Phytochemistry》1984,23(9):1947-1950
The known 10-acetoxy-8,9-epoxythymolisobutyrate and the new 8,9-dihydroxy-10-acetoxythymolisobutyrate and 8,9,10-trihydroxythymol have been isolated from the thallus of Eupatorium glechonophyllum. The acetonide of the last compound was also obtained. The possibility that the new compounds are artefacts is discussed. 相似文献
23.
Domènech J Bofill R Tinti A Torreggiani A Atrian S Capdevila M 《Biochimica et biophysica acta》2008,1784(4):693-704
Tetrahymena pyriformis MT1 (TpyMT1) is a model among ciliate metallothioneins (MTs). Here, we report on the analytic (ICP-AES, GC-FPD), spectroscopic (CD, UV-Vis, Raman) and spectrometric (ESI-MS) characterization of its recombinant Cd(II)-, Zn(II)- and Cu(I)-complexes, and of those formed during in vitro Zn/Cd and Zn/Cu replacement. In the presence of Cd(II), TpyMT1 renders a major Cd 11-TpyMT1 species, which is also the final step reached in the in vitro Zn/Cd exchange process in Zn 11-TpyMT1. Spectroscopic data supports a different folding of the isostoichiometric Cd 11- and Zn 11-TpyMT1 complexes. Unexpectedly, TpyMT1 biosynthesis in Zn(II)-rich cultures was sensitive to the aeration degree, so that high oxygenation rendered undermetalated, partially-oxidized, complexes (Zn9-TpyMT1). Biosynthesis in Cu(I)-rich media rendered extremely heterogeneous mixtures of CuxZny-species (x+y=8-20), where the higher the aeration, the higher the Zn(II) content. The complexity of these samples was reproduced during the Zn/Cu replacement, as the number of generated species increased gradually with the addition of copper to Zn(11)-TpyMT1. According to our results, a clear preference of TpyMT1 for Cd(II) binding, rather than for Zn(II), and especially Cu(I) can be postulated. This character is totally consistent with the induction pattern of the TpyMT1 gene and the postulated role of TpyMT1 in Cd-detoxification. 相似文献
24.
D Marone G Panio DB Ficco MA Russo P De Vita R Papa D Rubiales L Cattivelli AM Mastrangelo 《Molecular genetics and genomics : MGG》2012,287(9):741-753
Diversity array technology (DArT) markers are largely used for mapping, genetic diversity, and association mapping studies. For years, they have been used as anonymous genomic markers, as their sequences were not known. As the sequences of 2,000 wheat DArT clones are now available, this study was designed to analyze these sequences with bioinformatic approaches, and to study the genetic features of a subset of 291 markers positioned on the A and B genomes in three durum wheat genetic maps. A set of 1,757 non-redundant sequences was identified, and used as queries for similarity searches. Analysis of the genetic positions of markers corresponding to nearly identical sequences indicates that redundancy of sequences is one of the factors that explains the clustering of these markers in specific genomic regions. Of a total of 1,124 DArT clones (64?%) that represent putatively expressed sequences, putative functions are proposed for more than 700 of them. Of note, many clones correspond to genes that are related to disease resistance, as characterized by leucine-rich repeat domains, and 40 of these clones are positioned in the three genetic maps presented in this study. Finally, DArT markers have been used to find syntenic regions in the Brachypodium and rice genomes. In conclusion, the analyses herein presented contribute to explain the main features of DArT markers observed in genetic maps, as clustering in short chromosome regions. Moreover, the attribution of putative gene functions for more than 700 sequences makes these markers an optimal tool for collinearity studies or for the identification of candidate genes. 相似文献
25.
The cellular composition of the blood, anterior kidney, spleen and thymus of turbot Scophrhalmus maximus L., aged 1 + was determined. Ninety-four per cent of blood cells belonged to the erythrocyte lineage of which 82% were mature erythrocytes. The leucocytes, which represented 4.5% of the blood cells, were mainly lymphocytes (50%). The presence of crythroblasts in the anterior kidney and the spleen demonstrated an erythropoietic activity in both organs. However, this activity appeared to be prevalent in the spleen which also appeared to act as a storage zone for erythrocytes and as the centre point for thrombopoiesis. Although 96% of the anterior kidney cells were leucocytes, the number of white cells per gram of organ was higher in the spleen. 相似文献
26.
In Eubacteria, de novo translation of some internal cistrons may be inefficient or impossible unless the 5' neighboring cistron is also translated (translational coupling). Translation reinitiation is an extreme case of translational coupling in which translation of a message depends entirely on the presence of a nearby terminating ribosome. In this work, the characteristics of mRNA cis-elements inducing the reinitiation process in Escherichia coli have been investigated using a combinatorial approach. A number of novel translational reinitiation sequences (TRSs) were thus identified, which show a wide range of reinitiation activities fully dependent on a translational coupling event and unrelated to the presence/absence of secondary structure or mRNA stability. Moreover, some of the isolated TRSs are similar to intercistronic sequences present in the E. coli genome. 相似文献
27.
28.
Clifford Jacobs Brendon Pearce Mornè Du Plessis Nisreen Hoosain Mongi Benjeddou 《Genetics and molecular biology》2014,37(2):350-359
Human organic cation transporter 1 is primarily expressed in hepatocytes and mediates the electrogenic transport of various endogenous and exogenous compounds, including clinically important drugs. Genetic polymorphisms in the gene coding for human organic cation transporter 1, SLC22A1, are increasingly being recognized as a possible mechanism explaining the variable response to clinical drugs, which are substrates for this transporter. The genotypic and allelic distributions of 19 nonsynonymous and one intronic SLC22A1 single nucleotide polymorphisms were determined in 148 healthy Xhosa participants from South Africa, using a SNAPshot® multiplex assay. In addition, haplotype structure for SLC22A1 was inferred from the genotypic data. The minor allele frequencies for S14F (rs34447885), P341L (rs2282143), V519F (rs78899680), and the intronic variant rs622342 were 1.7%, 8.4%, 3.0%, and 21.6%, respectively. None of the participants carried the variant allele for R61C (rs12208357), C88R (rs55918055), S189L (rs34104736), G220V (rs36103319), P283L (rs4646277), R287G (rs4646278), G401S (rs34130495), M440I (rs35956182), or G465R (rs34059508). In addition, no variant alleles were observed for A306T (COSM164365), A413V (rs144322387), M420V (rs142448543), I421F (rs139512541), C436F (rs139512541), V501E (rs143175763), or I542V (rs137928512) in the population. Eight haplotypes were inferred from the genotypic data. This study reports important genetic data that could be useful for future pharmacogenetic studies of drug transporters in the indigenous Sub-Saharan African populations. 相似文献
29.
30.
María J. Barrero Borja Sese Bernd Kuebler Josipa Bilic Stephanie Boue Mercè Martí Juan Carlos Izpisua Belmonte 《Cell reports》2013,3(4):1005-1011
Highlights? Macrohistone variants are regulated during reprogramming and differentiation ? The levels of macrohistone variants modulate the efficiency of reprogramming ? MacroH2A.1 occupies pluripotency and differentiation genes in keratinocytes ? MacroH2A.1 occupancy prevents the gain of H3K4me2 during reprogramming 相似文献