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At least 19 recordsLinked to original sources
PubMed1978

Isoelectric focusing studies on the beta-fructofuranosidases and alpha-glucosidases of Streptococcus mitis.

Extracts of Streptococcus mitis ATCC 903 were analysed for beta-fructofuranosidase and alpha-glucosidase activities by isoelectric focusing in thin-layer polyacrylamide gels combined with zymogram procedures. Three bands of activity were visualized in the gels after incubation with sucrose (pI 4.05, 4.25 and 4.85) and three other bands after incubation with p-nitrophenyl alpha-D-glucopyranoside (pI 3.90, 4.45 and 4.65). The enzymes responsible for the reaction with sucrose were identified as beta-fructofuranosidases (EC 3.2.1.26) for the following reasons: identical enzyme bands were visualized in the gels after incubation with raffinose; no enzyme bands appeared in the gel after incubation with the alpha-glucosides maltose, turanose, trehalose and melezitose; and the soluble fraction hydrolysed sucrose to equimolar amounts of glucose and fructose.

Glucosidases↗
PubMedDate not supplied

[Methods of increasing the activity of extracellular esterase, beta-fructofuranosidase and proteases of wine yeast].

Upon regular fermentation changes in the activity of the enzymes esterase, beta-fructofuranosidase and protease of the yeast Saccharomyces mini of the Parkent I race were examined. The maximum activity of the enzymes occurred in the stationary phase of the yeast growth. An increase in the activity of the above enzymes was shown possible during a prolonged stabilization of the stationary conditions in the process of a continuous chemostat cultivation of wine yeast.

Esterases↗
PubMed1979

Preparation of high-fructose syrup from the tubers of the Jerusalem artichoke (Helianthus tuberosus L.

Fructose has recently received much attention due to renewed interest in natural sweeteners. In addition, fructose has some advantages to sucrose in sweetness, solubility, viscosity, and dental health characteristics. Fructose is deposited as storage fructans of the inulin (beta-1,2) type in tubers and rhizomes of the Compositae family. The utilization of the Jerusalem artichoke (Helianthus tuberosus) tuber as a source of fructose syrup is discussed. This plant has the potential to produce more sugar per acre than corn or sugar beets. In addition, the artichoke has higher frost resistance and lower heat unit requirements than corn and is somewhat more tolerant to low moisture conditions than sugar beets. A high quality fructose syrup can be produced from artichoke tubers. The extraction step was found to be particularly important since development of adverse colors and flavors must be prevented. The fructans may be acid or enzyme hydrolyzed but the latter method gave a higher quality syrup. Ion-exchange resins and activated charcoal were effective in removing coloring and flavoring materials, and also reduced other noncarbohydrate constituents. Since the enzymatic hydrolysis of the fructans is an attractive alternative to acid hydrolysis, a process was developed for producing and purifying a special beta-fructofuranosidase (inulase) from Saccharomyces fragilis. Inulase has a much higher specificity for fructans than commerically available beta-fructofuranosidase (invertase).

Carbohydrates↗
PubMed1977

Permeability of the cell envelope and osmotic behavior in Saccharomyces cerevisiae.

Bakers' yeast (Saccharomyces cerevisiae) was equilibrated with distilled water and then packed into standardized pellets by centrifugation. The fractional space (S value) that was accessible to passive permeation was probed with a variety of mono- and divalent salts, mono- and disaccharides, polyols, substrates and products of beta-fructofuranosidase (EC 3.2.1.26) and acid phosphatase (EC 3.1.3.2), and a cross-linked polymer of sucrose (Ficoll 400). A simple but very reproducible method was developed to measure pellet volume. At the limit of zero osmolality for bathing medium, the interstitial space was 0.223 ml/ml of pellet, and the aqueous volume of cell envelopes was 0.117 ml/ml of pellet. Thus the cell envelope for this yeast, under these conditions, was approximately 15% of the total cell volume. At a finite osmolality, the space in a yeast pellet that was accessible to salt was accounted for by the sum of initial interstitial space, the volume of the cell envelopes, and the volume of water abstracted from the cells by osmosis. Plots of S value versus osmolality were linear for uncharged probes and curvilinear for all salts. When Ficoll and potassium thiocyanate were presented to the yeast in admixture, the S values for the salt increased continuously over the range of osmolality studied. However, the S values for Ficoll 400 (which did not penetrate the cell wall) were lower by an amount equilivalent to the cell envelopes; they increased in parallel with the S curve for salt up to 1.15 osmol/kg and then plateaued. The results support the concept of incipient plasmolysis at 1.15 osmol/kg, and the separation of protoplasm from the cell wall is indicated with more concentrated solutions. Such cells were still viable if slowly diluted in distilled water, but they were injured by the shock of rapid dilution. However, shocking the cells did not release beta-fructofuranosidase into the medium. The complete accessibility of salts toward killed cells was demonstrated with yeast that had been pretreated with heat, organic solvents, or glutaraldehyde.

Acid Phosphatase↗
PubMed1976

Distribution of membranes, especially of plasma-membrane fragments, during zonal centrifugations of homogenates from glucose-repressed Saccharomyces Cerevisiae.

1. The distributions of several enzymes and other marker components were examined after zonal centrifugations of whole homogenates from glucose-repressed Saccharomyces cerevisiae on sucrose and iso-osmotic Ficoll, and the composition and morphology of the fractions were investigated. 2. After high-speed zonal centrifugation most of the protein, acid and alkaline phosphatases, alkaline pyrophosphatase, adenosine monophosphatase, beta-fructofuranosidase, alpha-mannosidase, NADPH-cytochrome c oxidoreductase and an appreciable amount of phospholipid and sterol were non-sedimentable, i.e. were at densities below 1.09 (g/cm3). Most of the RNA was at p=1.06-1.08 in Ficoll and at p=1.09-1.11 in sucrose. 3. The bulk of the Mg2+-dependent adenosine triphosphatase (Mg-ATPase) was coincident with the main peak of phospholipid and sterol, at median density 1.10, which was also rich in smooth-membrane vesicles. In Ficoll, a minor peak of phospholipid and sterol at p-1.12-1.15 contained a smaller part of the oligomycin-insensitive Mg-ATPase and heavy membrane fragments. In sucrose, several minor peaks of Mg-ATPase were in the mitochondrial density range, and a peak of oligomycin-insensitive Mg-ATPase coincident with a minor peak of phospholipid and sterol at around p-1.25 contained heavy membrane fragments of high carbohydrate content, especially mannose. 4. Further purification of the oligomycin-insensitive Mg-ATPase containing membrane preparations was performed on Urografin gradients. 5. It is argued that the oligomycin-insensitive Mg-ATPase containing membranes are fragments of the plasma membrane, but have different densities because they contain different amounts of glycoprotein particles.

Acid Phosphatase↗
PubMed1975

Enzymic hydrolysis of di-D-fructofuranose 1, 2'; 2, 3' dianhydride with Arthrobacter ureafaciens.

Enzymic hydrolysis of di-D-fructofuranose 1, 2'; 2, 3' dianhydride with the bacteria Arthrobacter ureafaciens was studied to elucidate its mechanism. Hydrolysis of the difructose dianhydride to D-fructose, which did not occur with yeast invertase [EC 3.2.1.26], was found to occur on incubation with an enzyme preparation from an autolysate of the above bacteria. However, incubation with enzyme which had been treated at 60 degrees for 30 min yielded an intermediate hydrolysis product. The product isolated was found to be inulobiose and to be hydrolyzed to D-fructose by the original enzyme, as well as by yeast invertase. It was thus shown that the hydrolysis of the difructose dianhydride to D-fructose with the crude enzyme took place not in a single step but in two separate steps at 2, 3' and 1, 2' linkages. It was not determined whether the entire process is mediated by one and the same beta-fructofuranosidase or by different enzymes.

Anhydrides↗
PubMed1979

Isolation and characterization of protoplasts from Saccharomyces rouxii.

Cells of the osmotolerant yeast Saccharomyces rouxii were transformed to protoplasts in good yield (85%) by digesting cell walls with snail-gut enzyme in the presence of 10 mM dithioerythritol, 0.1 M sodium phosphate buffer (pH 6.8), and 2.0 M KCl. The requirement for 2.0 M KCl compares with that for S. bisporus var. mellis (another osmotolerant species) and contrasts with the 0.3 to 0.8 M KCl concentrations used in the preparation of most yeast protoplasts. Short digestions (60 min or less) produced mostly spheroplasts; longer incubations (90 min or more) yielded mostly protoplasts as judged by electron micrographs. These protoplasts could be transferred to 1.0 M KCl or 2.0 M sorbitol without lysing, but lysis was pronounced in 0.5 M KCl or 1.0 M mannitol and complete in 0.02 M KCl. Protoplasts were separated from isolated cell wall remnants and debris by centrifugation on a linear gradient of Ficoll 400 (35 to 17.5%, wt/vol) containing 2.0 M KCl. Both crude and fractionated protoplast preparations contained vesicles which were identified with the periplasmic bodies of whole cells. Some of the periplasmic bodies were connected to protoplasts by fine pedicels; others appeared free. Independent degeneracy of periplasmic bodies was occasionally observed. beta-Fructofuranosidase (EC 3.2.1.26) activity is cryptic (physically) in cells of S. rouxii in contrast to the expressed enzyme (periplasmic space) of other Saccharomyces species. This enzyme remains cryptic in protoplast preparations of S. rouxii but is expressed upon lysis. The same specific activities were found per unit cell or protoplast. The possible association of the cryptic enzyme with periplasmic bodies is discussed.

Organoids↗
PubMedDate not supplied

[Method for immobilization of enzymic preparations catalyzing the splitting of low-molecular substrates].

A new method is suggested for immobilizing enzymes, catalyzing the splitting of low-molecular substrates. It consists in applying the layer of the enzymic preparation with a filler and a stabilizer onto the inert carrier by the rolling-up method in the dredging box and the subsequent coating of particles with a semipermeable film. The efficiency of the mentioned method is examined in two enzymic preparations: beta-galactosidase and beta-fructofuranosidase. Its advantages are discussed, the main of which are the simplicity of technology possibilities of using the enzymes technical preparations, maximal preservation of native properties.

Drug Stability↗
PubMedDate not supplied

[Ion exchange purification of some enzymes on KMT carboxyl cation exchanges].

Highly purfied preparations of the enzymes--yeast beta-fructofuranosidase, fungal beta-galactosidase and bacterial proteases have been isolated from crude preparations or culture liquids by adsorption on KMT microporous carboxyl cation exchanger. During desorption the enzyme activity has fully recovered and the specific activity increased 4.5-fold for beta-galactosidase and 54-fold for proteases.

Bacillus subtilis↗
PubMed1990

Production, thermal stability and immobilisation of inulinase from Fusarium oxysporum.

Fusarium oxysporum produced maximum extracellular inulinase after 9 days of its growth at 25 degrees C on a medium (pH 5.5) containing 3% fructan and 0.2% sodium nitrate. The level of this enzyme decreased on the addition of either glucose, fructose, galactose or sucrose to F. oxysporum already growing on a fructan-containing medium. A significant increase in invertase production which resulted in an increase of the invertase/inulinase (S/I) ratio, was observed on addition of inulin to this fungus growing on other carbon sources. Glycerol (10%) gave better protection to inulinase against thermal denaturation at 50 degrees C compared to ethylene glycol and sorbitol. Inulinase immobilised in polyacrylamide gel retained 45% of its original activity. The immobilised enzyme showed a higher optimum temperature (45 degrees C) compared to free enzyme (37 degrees C). The immobilised enzyme after storage at 25 degrees C for 96 h showed 58% activity. Thermal stability of entrapped inulinase increased in the presence of inulin.

Alcohols↗
PubMed1992

Stability, quaternary structure, and folding of internal, external, and core-glycosylated invertase from yeast.

The role of carbohydrate chains for the structure, function, stability, and folding of glycoproteins has been investigated using invertase as a model. The protein is encoded by several different genes, and its carbohydrate moiety is heterogeneous. Both properties complicate physicochemical comparisons. Here we used the temperature-sensitive sec18 secretion mutant of yeast with a single invertase gene (SUC2). This mutant produces the carbohydrate-free internal invertase, the core-glycosylated form, and, at the permissive temperature, the fully glycosylated external enzyme, all with identical protein moieties. The core-glycosylated enzyme resembles the nascent glycoprotein chain that folds in the endoplasmic reticulum. Therefore, it may be considered a model for the in vivo folding of glycoproteins. In addition, because of its uniform glycosylation, it can be used to investigate the state of association of native invertase. Glycosylation is found to stabilize the protein with respect to thermal denaturation and chaotropic solvent components; the stabilizing effect does not differ for the external and the core-glycosylated forms. Unlike the internal enzyme, the glycosylated forms are protected from aggregation. Native internal invertase is a dimer (115 kDa) whereas the core-glycosylated enzyme is a mixture of dimers, tetramers, and octamers. This implies that core-glycosylation is necessary for oligomerization to tetramers and octamers. Dimerization is required and sufficient to generate enzymatic activity; further association does not alter the specific activity of core-glycosylated invertase, suggesting that the active sites of invertase are not affected by the association of the dimeric units. Reconstitution of the glycosylated and nonglycosylated forms of the enzyme after preceding guanidine denaturation depends on protein concentration. The maximum yield (approximately 80%) is obtained at pH 6-8 and protein concentrations < or = 4 micrograms/mL for the nonglycosylated and < or = 40 for the glycosylated forms of the enzyme. The lower stability of the internal enzyme is reflected by a narrower pH range of reactivation and enhanced aggregation. As indicated by the sigmoidal reactivation kinetics at low protein concentration both folding and association are rate-determining.

Enzyme Reactivators↗
PubMed1990

Properties and repeated use of a reversibly soluble-insoluble yeast lytic enzyme.

A yeast lytic enzyme was covalently immobilized on an enteric coating polymer, Eudragit S, that is reversibly soluble and insoluble (S-IS) depending on the pH of the reaction medium. The yeast lytic enzyme immobilized on Eudragit S (Y-E) showed a sharp response of solubility to slight changes in pH without decrease in enzymatic activity. The specific activity per amount of enzyme protein of Y-E for dry yeast cells was about two-thirds that of the native enzyme. In both lysis reactions of dry and pressed baker's yeast cells, changing the pH of the reaction medium from 7.0 to 4.8 at an appropriate interval allows the insoluble Y-E and the reaction products (soluble protein for dry yeast cells and invertase and soluble protein for pressed baker's yeast cells) to be repeatedly separated. The reaction method using a reversible S-IS enzyme is a promising procedure for repeated use of the enzyme in a heterogeneous reaction system containing yeast cells as a substrate.

Acrylic Resins↗
PubMedDate not supplied

Immobilization of invertase through its carbohydrate moiety on Ocimum basilicum seed.

Yeast invertase, a glycoprotein, was covalently coupled to Ocimum basilicum seeds either through its protein or carbohydrate moiety. Of the various methods investigated, binding of the enzyme through its carbohydrate moiety resulted in the retention of considerably higher amounts of enzyme activity. Immobilized invertase showed a shift in the pH optimum toward the alkaline side without appreciable change in temperature optimum. However, the immobilized preparation was more thermostable than the free enzyme. Invertase bound to the seeds could be used repeatedly for the hydrolysis of sucrose syrups in a batch process without appreciable loss in activity. The seeds could serve as an inexpensive, ready-to-use, natural pellicular polysaccharide support for immobilizing enzymes.

Carbohydrates↗
PubMed1992

Glycosylation inhibits the interaction of invertase with the chaperone GroEL.

During refolding and reassociation of chemically denatured non-glycosylated invertase from Saccharomyces cerevisiae, aggregation competes with correct folding, leading to low yields of reactivation (Kern et al. (1992) Protein Sci. 1, 120-131). In the presence of the chaperone GroEL, refolding is completely arrested. This suggests the formation of a stable complex between GroEL and non-native non-glycosylated invertase. Addition of MgATP results in a slow release of active invertase from the chaperone complex. When GroEL/ES and MgATP are present during refolding, the final reactivation yield increases from 14% to 36%. In contrast, refolding of the core-glycosylated and the high-mannose glycosylated forms of invertase is not arrested by GroEL. Only a short lag phase at the beginning of reactivation and a slightly increased reactivation yield (64% to 86% for core-glycosylated and 62% to 76% for external invertase) indicate a weak interaction of the glycosylated forms with the chaperone.

Bacterial Proteins↗