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21.
L. Vannini R. Lanciotti F. Gardini M. E. Guerzoni 《World journal of microbiology & biotechnology》1996,12(1):85-90
Chemical changes in the medium, induced by the fermentative species Lactobacillus plantarum and Lactobacillus brevis and by the enzymatic action of a proteolytic, spoilage species, Yarrowia lipolytica, were analysed using Fourier-transform i.r. spectroscopy (FTIR). Changes in the absorbance data over time could be modelled using one of the more current predictive, mathematical models of microbial growth, such as the Gompertz equation. Moreover, a linear correlation between FTIR data (expressed as absorbance of some selected peaks) and viability data (expressed as log10 c.f.u./g or ml) was observed during the fermentation process, both for L. plantarum and L. brevis. 相似文献
22.
Gaetano Barbato Daniel O. Cicero Elisabetta Bianchi Antonello Pessi Renzo Bazzo 《Journal of biomolecular NMR》1996,8(1):36-48
Summary We describe the high-resolution structure by NMR of two peptides that belong to a combinatorial library based on the zinc-finger motif. The library represents, to the best of our knowledge, the first example of a conformationally homogeneous peptide library and was obtained by introducing random residues in five positions of the -helical portion of a 26-residue consensus peptide (CP1) belonging to the Cys2-Hys2 zinc-finger family. The result was shown to be a highly homogeneous -helical library (Bianchi et al., 1995). The structures of the parent compound (CP1) and of a representative member (CP1m) that was selected by screening the library with a monoclonal antibody are compared in detail as an example of the very high stability of the zinc-finger scaffold upon sequence variability. The two peptides exhibit an extremely high degree of structural similarity. The use of this type of conformationally constrained combinatorial library might represent a step forward in the design of peptidomimetics, as it considerably accelerates the process of the identification of the spatial relationship among the pharmacophoric groups.Abbreviations
t-Bu
tert-butyloxycarbonyl
- Fmoc
9-fluorenylmethoxycarbonyl 相似文献
23.
24.
25.
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
26.
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
27.
Amino acid composition of zein molecular components 总被引:1,自引:0,他引:1
Elisabetta Gianazza Vittorio Viglienghi Pier Giorgio Righetti Francesco Salamini Carlo Soave 《Phytochemistry》1977,16(3):315-317
Zein extracted from maize endosperm has been fractionated into four polypeptide chains, having the following MWs 23 000, 21 000, 13 500 and 9600. By amino acid analysis the two smaller MW chains (representing 30% of total zeins) have been found to be zein-type molecules. These two chains are thought to be responsible for zein granule formation via -S-S- bridges. Zein is also highly heterogeneous in charge, and is resolved into at least 15 components, with pI's in the pH range 5–9. As demonstrated by amino acid analysis, part of this heterogeneity is due to spot mutations in some of the genes responsible for zein synthesis. 相似文献
28.
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
29.
30.
Elisabetta Gianazza Francesco Chillemi Marcello Duranti Pier Giorgio Righetti 《Journal of biochemical and biophysical methods》1983,8(4):339-351
A new method for peptide analysis and purification is described, based on isoelectric focusing in immobilized pH gradients. On the analytical scale, the peptide zones can now be revealed by an stain for primary and secondary amino group (e.g. ninydrin, fluorescamine, dansyl chloride) since the buffering species, unlike conventional carrier ampholytes, contain only carboxyl and tertiary amino groups. For preparative purposes, conditions have been described to remove most contaminants (e.g. unreacted monomers, non-cross-linked, short polyacrylamide chains) from the gel matrix before the electrophoretic run. However, ca. 2% of the gel dry mass is still present as extractable material. The focused peptides can be recovered in higly yields (ca. 90%) with a fairly high degree of purity (75%), the contaminants being mostly components eluted from the polyacrylamide gel. 相似文献