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1

Digitale Medien

Analytical differentiation of wine fermentations using pure and mixed yeast cultures (1991)

Moreno, Juan J. ; Millán, Carmen ; Ortega, José M. ; [weitere]

Springer

Journal of industrial microbiology and biotechnology 7 (1991), S. 181-189

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ISSN: 1476-5535

Schlagwort(e): Saccharomyces cerevisiae ; Torulaspora delbrueckii ; Aroma

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Summary Thirty-three fermentations of Pedro Ximénez grapes, collected in three degrees of ripeness, were carried out by inoculation with three types of inoculum: pure cultures ofSaccharomyces cerevisiae races and ofTorulaspora delbrueckii, indigenous yeasts, and mixed cultures of indigenous yeasts enriched with the pure cultures. By means of variance analysis 21 compounds were determined whose final concentrations in the wines significantly depended on the musts, the inocula or both. Eleven products that depended significantly on the inocula were subjected to a discriminant analysis in which most of the pure cultures gathered in a discriminant space area different from that occupied by the indigenous yeasts. The centroids corresponding to most of the mixed cultures were shifted to the central area of the discriminant space, moved away from their corresponding pure cultures and approached the indigenous yeasts. The results show a high similarity between the fermentations carried out with mixed cultures with the addedS. cerevisiae races and those fermentations carried out with the indigenous yeasts, with regard to those compounds which were significantly dependent on the inocula.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01575881

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2

Digitale Medien

Competitive adsorption of magnesium and calcium ions onto synthetic and biological apatites (1992)

Aoba, T. ; Moreno, E. C. ; Shimoda, S.

Springer

Calcified tissue international 51 (1992), S. 143-150

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ISSN: 1432-0827

Schlagwort(e): Adsorption ; Magnesium ; Calcium ; Apatite crystals ; Enamel ; Dentin ; Bone

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin , Physik

Notizen: Summary Magnesium (Mg) is a conspicuous constituent of hard tissues but its possible role in biomineralization is poorly understood. It is possible that Mg2+ adsorbed onto bioapatites may contribute to the modulation of crystal growth as such inhibitory activity has been reported for synthetic apatites. The present study was undertaken to determine the adsorption isotherms of Mg ions onto synthetic apatites and biominerals in tooth and bone tissues in the presence of other ions of natural occurrence. Synthetic crystals used as adsorbents were hydroxyapatite and, as a better prototype for the biomineral, Mg-containing carbonatoapatite. Human enamel and dentin materials were obtained from extracted, caries-free, permanent teeth. Porcine dentin materials at two developmental stages were obtained from erupted deciduous and unerupted permanent teeth of a 6-month-old slaughtered piglet. Porcine bone was obtained from the cortical portion of the mandible of the same animal. All biomineral samples were pulverized and then treated by plasma ashing (deproteination) at about 60°C. Each of the powdered samples was equilibrated in solutions containing various initial concentrations of Mg2+, Ca2+, and Na+ (or K+) as nitrate salts. Following equilibration, concentrations (and activities) of magnesium and calcium ions in the experimental solution were determined. The pH values of the equilibrium solutions were in the range of 6.2–6.5. Experimental data of the Mg adsorption onto hydroxyapatite were interpreted on the basis of a Langmuir-type model for binary systems assuming competition of Mg2+ and Ca2+ for the same adsorption sites on the crystal surfaces of the apatites. According to this model, the adsorbed Mg is expressed as a function of the ionic activity ratio (Mg2+)/(Ca2+) in the equilibrium solution. The model contains two parameters, the adsorption selectivity constant Ks and the maximum number of adsorption sites N (μmol/g). The numerical values of Ks were similar for all adsorbents used (synthetic and biological) and indicated the preferential adsorption of Ca2+ probably due to spacial restrictions extending to the very surface of the crystals. The initial level of Mg2+ in the surface pool was different in the various biominerals, probably reflecting the composition of fluid in which the biominerals were formed. Whereas the surface pool of Mg of human enamel was marginal, only 5% of the total Mg, significant fractions of the total Mg in human and porcine dentins (about 20–30%), and porcine bone (about 40%) existed on the crystal surfaces. There were significant differences in the total Mg and the value of the parameter N between young (unerupted) and mature (erupted) dentin minerals. It was ascertained that the occupancy of adsorption sites by Mg ions became greater with maturation of the dentin tissues. The overall results suggest that the Mg-mineral interaction in tooth and bone tissues may be a highly tissue-specific process, presumably reflecting differences in fluid composition (particularly Ca and Mg activities) responsible for biomineralization.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00298503

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3

Digitale Medien

Effect of human salivary proteins on the precipitation kinetics of calcium phosphate (1979)

Moreno, E. C. ; Varughese, K. ; Hay, D. I.

Springer

Calcified tissue international 28 (1979), S. 7-16

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ISSN: 1432-0827

Schlagwort(e): Salivary proteins ; Adsorption ; Hydroxyapatite ; Precipitation inhibitors ; Crystal growth

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin , Physik

Notizen: Summary Inhibition of calcium phosphate precipitation in saliva, and prevention of the formation of mineral accretions on tooth surfaces, has been ascribed to the existence of inhibiting salivary macromolecules. Marked reductions in the crystal growth rate of hydroxyapatite (HA) seeds were measured in supersaturated solutions containing either of two proline-rich proteins, PRP1 or PRP3, or statherin; the three macromolecules were isolated from human parotid saliva. The reductions were also observed when the HA seeds were pretreated with solutions of the macromolecules before adding them to the supersaturated calcium phosphate solution. This effect was very similar in the case of the two PRPs and it was directly related to the extent of adsorption site coverage of these proteins on the HA seeds. The effect of statherin was larger than anticipated from its adsorption behavior. However, comparison on the basis of number of moles adsorbed per unit area of HA shows that the PRP are more effective inhibitors than statherin. The macromolecule concentrations used were considerably lower than those in the salivery secretions, therefore these macromolecules could readily prevent mineral accretion on tooth surfaces through their adsorption onto the enamel surface.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02441212

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4

Digitale Medien

Inhibition of apatite crystal growth by the amino-terminal segment of human salivary acidic proline-rich proteins (1984)

Aoba, T. ; Moreno, E. C. ; Hay, D. I.

Springer

Calcified tissue international 36 (1984), S. 651-658

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ISSN: 1432-0827

Schlagwort(e): Salivary proteins ; Hydroxyapatite ; Adsorption ; Precipitation-inhibitor ; Phosphoserine

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin , Physik

Notizen: Summary Inhibition of seeded apatitic crystal growth by human salivary acidic proline-rich phosphoproteins (PRP) has been related to their adsorption onto the apatite seeds. The amino-terminal 30-residue segment of the PRP makes an important contribution to this adsorption. This peptide (PRP1(T1)) and its dephosphorylated analogue from PRP3 (PRP3(T1)DP) were prepared. They have identical sequences, except the phosphates at residues 8 and 22 in PRP1(T1) are absent from PRP3(T1)DP. Adsorption of these peptides onto hydroxyapatite and their effect on crystal growth from a defined supersaturated solution was studied. Adsorption behavior was adequately described by the Langmuir adsorption isotherm. The adsorption affinity constant of PRP1(T1) (K=20,200 ml/µmol) was more than 10 times the corresponding value for PRP3(T1)DP (1,800 ml/µmol), and similar to that of the parent protein, PRP1 (26,200 ml/µmol). Inhibition of crystal growth by the peptides was interpreted in terms of the fractional coverage of the maximum number of adsorption sites (as derived from the adsorption isotherms), suggesting that the molecules block, by adsorption, specific growth sites on these surfaces. Comparison of precipitation kinetics showed that PRP1(T1) is a more effective inhibitor than PRP3(T1)DP at the same initial concentration (10−6−10−7 M). However, on the basis of per mol adsorbed, PRP3(T1)DP displays a greater inhibitory activity; such a behavior is consistent with a more open molecular structure which blocks more growth sites per mol adsorbed than PRP1(T1). Because of its high affinity constant, preadsorbed PRP1(T1) remains in the condensed state in the supersaturated solution used, whereas the preadsorbed PRP3(T1)DP molecules desorb to some extent, resulting in a decrease in inhibitory activity. The results show that the amino-terminal segment of the PRP and the two phosphoserine residues present in this segment are particularly important in the function proposed for these proteins in the oral environment.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02405385

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5

Digitale Medien

Adsorption of molecules of biological interest onto hydroxyapatite (1984)

Moreno, E. C. ; Kresak, M. ; Hay, D. I.

Springer

Calcified tissue international 36 (1984), S. 48-59

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ISSN: 1432-0827

Schlagwort(e): Salivary proteins ; Adsorption ; Thermodynamics ; Kinetics ; Hydroxyapatite

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin , Physik

Notizen: Summary Equilibrium and kinetic experiments were conducted to investigate the factors determining the adsorption of salivary macromolecules onto hydroxyapatite. Using amino acids and other small adsorbates, it was determined that the carboxyl attached to the α carbon does not appear to adsorb onto HA and the affinities of side-chain carboxyls are much smaller than that of the phosphate group (phosphoserine). Hydroxyl (serine) displays an extremely high affinity, but its adsorption site on HA is different and the number of such sites is much smaller than found for the rest of the functional groups investigated. It is shown that the information obtained from small molecules cannot be readily applied to prediction of the adsorption behavior of salivary macromolecules and polypeptides. The kinetics of adsorption of the salivary phosphopeptide statherin, a polyaspartate, and the salivary prolinerich phosphoprotein PRP3 are consistent with the reversibility of the adsorption process; no conclusion was possible in the case of the protein PRP1. Apparent irreversibility cannot be explained on the basis of multipoint binding or the properties of the carboxyl versus phosphate group; it appears that secondary structure determines to a significant extent the adsorption properties of the macromolecules. Calculation of the thermodynamic molar quantities of adsorption of PRP1, PRP3, andl-ASP onto HA showed that the process is entropically driven. The functional relationship between partial molar entropy and adsorption coverage is similar for the two proteins, but quite different from that for aspartate. Explanations for these results are advanced on the bases of changes in structure configurations and displacement of water from the adsorbate and the adsorbent surface, the second factor being the dominant one in the adsorption of a small molecule such asl-ASP.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02405293

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6

Digitale Medien

Evolution of C6, C8 and C10 acids and their ethyl esters in cells and musts during fermentation with threeSaccharomyces cerevisiae races (1994)

Zea, Luis ; Moreno, Juan ; Medina, Manuel ; [weitere]

Springer

Journal of industrial microbiology and biotechnology 13 (1994), S. 269-272

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ISSN: 1476-5535

Schlagwort(e): Wine ; Yeasts ; Fatty acids ; Ethyl esters ; Saccharomyces cerevisiae

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Summary The evolution of the cell and must contents of three short-chain fatty acids (C6, C8 and C10) and their ethyl esters during fermentations withSaccharomyces cerevisiae racescerevisiae, bayanus andcapensis were studied. The former is a fermentative yeast and the last two are ‘flor’ film yeasts. The acid concentrations in the musts increased throughout the alcoholic fermentations, and maximum cell concentrations of the fatty acids were reached after 48 h of fermentation. Maximum ester concentrations in the cells were attained after 48–72 h of fermentation. In the musts, ethyl octanoate and ethyl decanoate reached a peak also at this point, and ethyl hexanoate after 10 days. After 134 days,S. cerevisiae racecapensis formed a thick ‘flor’ film whileS. cerevisiae racebayanus developed a thin film andS. cerevisiae racecerevisiae formed no film. At this point, acid contents remained constant in the wines produced byS. cerevisiae racescerevisiae andbayanus, and decreased in those obtained with racecapensis. The ethyl ester contents tended to decrease with the exception of ethyl decanoate in the fermentations carried out byS. cerevisiae racescerevisiae andbayanus.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01569727

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7

Digitale Medien

The centromere and promoter factor 1, CPFI, of Saccharomyces cerevisiae modulates gene activity through a family of factors including SPT21, RPD1 (SIN3), RPD3 and CCR4 (1993)

McKenzie, Edward A. ; Kent, Nicholas A. ; Dowell, Simon J. ; [weitere]

Springer

Molecular genetics and genomics 240 (1993), S. 374-386

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ISSN: 1617-4623

Schlagwort(e): Saccharomyces cerevisiae ; Centromere and promoter factor ; Chromatin ; SPT ; Transcription

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract In Saccharomyces cerevisiae, the CPF1 gene encodes a ccntromere binding protein that also plays a role in transcription; cpf1 strains are methionine auxotrophs. In this paper we describe four strains that are methionine prototrophs despite containing a defective CPF1 gene. These strains, which contain mutations at either the SPT21, RPD1 (SINS), RPD3 or CCR4 loci, have defective centromere function and a chromatin structure around the CDEI elements in the MET25 promoter characteristic of strains lacking CPF1. This indicates that the roles of CPF1 in transcription, centromere function and chromatin modulation around CDEI sites are different. We propose that CPF1 functions to overcome the repressing action, mediated via inactive chromatin, of proteins such as SPT21 or RPDI (SIN3) on gene expression. The absence of proteins such as SPT21 or RPD1 (SIN3) relieves this respression and explains how methionine prototrophy is restored in the absence of CPF1.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00280389

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