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21.
22.
Luigi Valentini Elisabetta Gianazza Pier Giorgio Righetti 《Journal of biochemical and biophysical methods》1980,3(6):323-338
Basic equations have been derived linking the electrophoretic migration in a stationary pH gradient of simple, singly charged cations or anions and of mono- mono- valent ampholytes with the pKs of their ionizable groups. In the case of diprotic ampholytes, an equation and a curve are described calculating a correction factor to be applied to the mobility measurements, accounting for the influence of the opposite charge species on the mobility curve of the ion being measured. This correction factor is a function of ΔpK and increases exponentially with decreasing values of ΔpK. These theoretical considerations have been experimentally verified by running pH-mobility curves of colored compounds, such as methyl red, neutral red and dexorubicin. The pKs thus measured were in excellent agreement with the pKs obtained independently by spectrophotometric titrations. 相似文献
23.
Elisabetta Colletti Laura Frontali Claudio Palleschi Micheline Wesolowski Hiroshi Fukuhara 《Molecular & general genetics : MGG》1979,175(1):1-4
Summary In S. cerevisiae four isoacceptor mitochondrial tRNAs for serine have been separated by reversed phase chromatography. At least two of these species are products of different genes. In this work the deletion mapping technique has been used to locate two genes for tRNAser. The gene for tRNAser previously localized in the oli I region of the mitochondrial genome has been found to code for tRNA
ser
2
, and another gene coding for tRNA
ser
1
has been detected in the region where most of other tRNA genes are found. Results of fine mapping experiments allowed to localize this gene in the proximity of the gene for tRNAarg. 相似文献
24.
Heterogeneity of storage proteins in maize 总被引:1,自引:0,他引:1
The extensive charge heterogeneity of maize (Zea mays L.) zeins observed in isoelectric focusing (IEF) (about 15 bands with pI's in the pH range 6–9) has been found to be independent of extraction procedures or of endosperm development. Zeins do not stain for glycoproteins and exhibit only one lipoprotein component, with pI 3, representing 3–5% of the total protein.Zeins are very resistant to in vitro deamidation, at both acidic and alkaline pH, at high temperatures, and for rather prolonged times. On the basis of the zein content in acidic and basic amino acids, and of the respective pI's exhibited in IEF (mostly in the pH range 7–8) it has been calculated that at least 90% of the glutamic and aspartic acids (52 residues out of a total of 190) are present as asparagine and glutamine.Amino acid analysis of zein fractions isolated by preparative IEF has demonstrated changes in the composition of 18 amino acid residues. However, since these changes affect only neutral and hydrophobic residues, it is concluded that the observed zein heterogeneity is partly based on in vivo deamidation of glutamine and asparagine and partly to spot mutations in some of the genes responsible for zein synthesis.Abbreviations A
absorbance
- Bis
N,N-methylene bisacrylamide
- IEF
isoelectric focusing
- 2-ME
2-meroaptoethanol
- mol wt
molecular weight
- 62
opaque-2
- PAGE
polyacrylamide gel electrophoresis
- pI
isoelectric point
- PAS
periodic acid-Schiff stain
- SDS
sodium dodecyl sulphate
- ICA
trichloroacetic acid
- TEMED
N,N,N,N-tetramethyl ethylene diamine
- Z1
zein extracted with 55% isopropanol
- Z2
zein extracted with 55% isopropanol and 0.6% 2-ME
- Z 9.6
zein of mol wt 9600
- Z 13.5
zein of mol wt 13,500
- Z 21
zein of mol wt 21,000
- Z 23
zein of mol wt 23,000 相似文献
25.
26.
Susanna Salvadori Elisabetta Coluccia Federica Deidda Angelo Cau Rita Cannas Anna Maria Deiana 《Genetica》2012,140(10-12):429-437
The evolutionary pathway of Palinuridae (Crustacea, Decapoda) is still controversial, uncertain and unexplored, expecially from a karyological point of view. Here we describe the South African spiny lobster Jasus lalandii karyotype: n and 2n values, heterochromatin distribution, nucleolar organizer region (NOR) location and telomeric repeat structure and location. To compare the genomic and chromosomal organization in Palinuridae we located NORs in Panulirus regius, Palinurus gilchristi and Palinurus mauritanicus: all species showed multiple NORs. In J. lalandii NORs were located on three chromosome pairs, with interindividual polymorphism. In P. regius and in the two Palinurus species NORs were located on two chromosome pairs. In the two last species 45S ribosomal gene loci were also found on B chromosomes. In addition, the nature and location of telomeric repeats were investigated by FISH in J. lalandii, P. gilchristi, P. mauritanicus Palinurus elephas, and P. regius (Palinuridae, Achelata), and in Scyllarus arctus (Scyllaridae, Achelata): all these Achelata species showed the (TTAGG)n pentameric repeats. Furthermore, in J. lalandii these repeats occurred in all the telomeres and in some interstitial chromosomal sites, associated with NORs. 相似文献
27.
Uric Acid Amplifies Aβ Amyloid Effects Involved in the Cognitive Dysfunction/Dementia: Evidences From an Experimental Model In Vitro
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28.
The mitochondrial genome (mtDNA), due to its peculiar features such as exclusive presence of orthologous genes, uniparental inheritance, lack of recombination, small size and constant gene content, certainly represents a major model system in studies on evolutionary genomics in metazoan. In 800 million years of evolution the gene content of metazoan mitochondrial genomes has remained practically frozen but several evolutionary processes have taken place. These processes, reviewed here, include rearrangements of gene order, changes in base composition and arising of compositional asymmetry between the two strands, variations in the genetic code and evolution of codon usage, lineage-specific nucleotide substitution rates and evolutionary patterns of mtDNA control regions. 相似文献
29.
Penna S 《Trends in plant science》2003,8(8):355-357
Trehalose is a rare sugar with unique abilities to protect biomolecules from environmental stresses and is present in many bacteria, fungi and some desiccation-tolerant higher plants. Increasing trehalose accumulation in crop plants could improve drought and salinity tolerance. Transgenic plants have been developed with trehalose biosynthetic genes--a recent study on the stress-inducible overexpression of the bifunctional TPSP fusion gene in transgenic rice could offer novel strategies for improving abiotic stress tolerance in crop plants. 相似文献
30.
Meacci E Cencetti F Donati C Nuti F Farnararo M Kohno T Igarashi Y Bruni P 《Biochimica et biophysica acta》2003,1633(3):133-142
The bioactive lipid sphingosine 1-phosphate (S1P) is known to exert powerful biological effects through the interaction with various members of the endothelial differentiation gene (EDG) receptor family, recently renamed S1P receptors. In the present study, evidence is provided that differentiation of C2C12 myoblasts into myotubes was accompanied by profound changes of EDG/S1P receptor expression. Indeed, in differentiated cells a significant increase of EDG3/S1P3 together with a large decrease of EDG5/S1P2 expression at mRNA as well as protein level was detected. Moreover, S1P was capable to initiate the signalling pathways downstream to cytosolic Ca(2+) increase in myotubes, similarly to that observed in myoblasts, whereas the signalling of the bioactive lipid to phospholipase D (PLD), but not that of bradykinin (BK) or lysophosphatidic acid (LPA), was found impaired in differentiated cells. Intriguingly, overexpression of EDG5/S1P2, but not EDG1/S1P1 or EDG3/S1P3, potentiated the efficacy of S1P to stimulate PLD, strongly suggesting a role for EDG5/S1P2 in the signalling to PLD. This view was also supported by the marked reduction of S1P-induced PLD activity in myoblasts loaded with antisense oligodeoxyribonucleotides (ODN) to EDG5/S1P2. Furthermore, overexpression of EDG5/S1P2 rescued the coupling of S1P signalling to PLD in C2C12 myotubes. Experimental evidence here provided supports the notion that EDG5/S1P2 plays a dominant role in the coupling of S1P to PLD in myoblasts and that the down-regulation of the receptor subtype is responsible for the specific uncoupling of S1P signalling to PLD in myotubes. 相似文献