Mixture Of Galactose Research Articles

Diauxic Growth of Azotobacter vinelandii on Galactose and Glucose: Regulation of Glucose Transport by Another Hexose

The growth curve of Azotobacter vinelandii was biphasic when the organism was grown in a medium containing a mixture of galactose and glucose. Galactose was the primary carbon source; glucose was also consumed, but the rate at which it was consumed was lower than the rate at which galactose was consumed during the first phase of growth. Metabolic pathways for both sugars were induced. Cell cultures exhibited a second lag period as galactose was depleted. The length of this lag phase varied from 2 to 10 h depending on the pregrowth history of the cells. The second log growth phase occurred at the expense of the remaining glucose in the medium and was accompanied by induction of the high-maximum rate of metabolism glucose-induced glucose permease and increases in the levels of glucose metabolic enzymes. The second lag phase of diauxie may have been due to the time required for induction of the glucose-induced glucose permease.

Growth and metabolism of human tumor kidney cells on galactose and glucose

The culture kinetics of human tumor kidney cells (TCL 598) grown on microcarriers are compared with media initially supplemented with either glucose alone or a mixture of galactose and glucose. Growth rates and maximal cell densities are similar, but cellular death is much slower in galactose than in glucose. Galactose is metabolized at a much slower specific rate than glucose. Cells grown in the galactose medium show a different pattern of lactate and pyruvate metabolism compared to cells grown in the glucose medium. Growth with galactose also favours oxidation of glutamine to alanine.

Enzymatic Synthesis of Galactooligosaccharides by the Condensation Action of Thermostable .ALPHA.-Galactosidase from Pycnoporus cinnabarinus.

Three kinds of trisaccharides were synthesized using condensation action of α-galactosidase (EC 3.2.1.22) from pyrcnoporus cinnabarinus on the mixture of galactose and sucrose. The condensation products were isolated and their structures were investigated by acid and enzymatic hydrolysis, and methylation analysis. The three trisaccharides isolated were identified as raffinose, planteose, and 3G-α-galactosylsucrose. Conditions for synthesis of the trisaccharides by condensation action of the α-galactosidase were studied. The yield of the trisaccharides was approximately 15% based on the amount of galactose used, when α-galactosidase (40 units/ml) was incubated with 10% (w/v) galactose and 60% (w/v) sucrose for 48h at pH 5.0 and 60°C.

Characterization of Thermoanaerobacter Glucose Isomerase in Relation to Saccharidase Synthesis and Development of Single-Step Processes for Sweetener Production

Regulation of glucose isomerase synthesis was studied in Thermoanaerobacter strain B6A, which fermented a wide variety of carbohydrates including glucose, xylose, lactose, starch, and xylan. Glucogenic amylase activities and beta-galactosidase were produced constitutively, whereas the synthesis of glucose isomerase was induced by either xylose or xylan. Production of these saccharidase activities was not significantly repressed by the presence of glucose or 2-deoxyglucose in the growth media. Glucose isomerase production was optimized by controlling the culture pH at 5.5 during xylose fermentation. The apparent temperature and pH optima for these cell-bound saccharidase activities were as follows: glucose isomerase, 80 degrees C, pH 7.0 to 7.5; glucogenic amylase, 70 degrees C, pH 5.0 to 5.5; and beta-galactosidase, 60 degrees C, pH 6.0 to 6.5 Glucose isomerase, glucogenic amylase, and beta-galactosidase were produced in xylose-grown cells that were active and stable at 60 to 70 degrees C and pH 6.0 to 6.5. Under single-step process conditions, these saccharidase activities in whole cells or cell extracts converted starch or lactose directly into fructose mixtures. A total of 96% of initial liquefied starch was converted into a 49:51 mixture of glucose and fructose, whereas 85% of initial lactose was converted into a 40:31:29 mixture of galactose, glucose, and fructose.

Induction of balbiani ring puffing changes by sugars and alcohols in Chironomus thummi

The capacity of several substances to induce in Chironomus thummi larvae the repression of Balbiani ring 2 (BR2) and the coordinated activation of Balbiani ring 1 (BR1) has been evaluated. Hexoses as well as some disaccharides, except lactose, were efficient inducers. The pentoses tested failed to provoke puffing changes. Alcohols, such as ethanol and glycerol, showed a moderate capacity as inducers, whereas methanol and isopropanol were ineffective. When a mixture of galactose and glycerol was used, a significant acceleration of the response, at the puffing as well as the translational level, was observed. To search for common effects of different inducers, an attempt was first made to test whether the lowering of the inorganic phosphate level in the haemolymph could play a causal role in the shift of BR1/BR2 puffing as it does in the response of the Camptochironomus group. In C. thummi, we have found effective inducers which increased, decreased or did not modify the inorganic phosphate concentration in the haemolymph thus suggesting the independence of the induced puffing changes and phosphate level modifications.

Eliciting Antibodies in Chickens to Human Dimeric IgA Removal of Factors from Human Colostrum Depressing Anti IgA Antibody Production

Contrary to expectation chickens did not readily elicit antibodies to IgA dimers when untreated human colostrum was used as antigen. When colostrum was fractionated by means of a column of 8% granulated agarose equilibrated with 10mM phosphate buffer, pH 7.2, a major and a minor fraction were obtained. The major or "1st fraction" consisted of two components with sedimentation coefficients of 10.9 S and 14.1 S, respectively. The minor or "2nd fraction" consisted of components of S values ranging from 2 to 6 and small amounts of 10.9 and 14.1 S material. When chickens were immunized with the "1st fraction" antibodies to dimeric IgA were produced. When the "1st and 2nd fractions" of the column were remixed and used for immunization of chickens, the immune response was poor as when the chickens were injected with untreated colostrum. An immuno-depressing agent in colostrum was indicated. When rabbits were immunized with clarified human colostrum, antibodies against five antigens were elicited, one of the antigens being dimeric IgA. The purified agent suppressed antibody formation in chickens against the haemocyanin of Jasus lalandii. The "activity" is therefore not specific for IgA and the remaining four antigens in human colostrum. The purified component is a glyco-protein with a hexose content in excess of 10%. The derivatized sugars prepared from it were shown by gas liquid chromatography to be an equimolar mixture of galactose, mannose and fucose. The molecular weight (Mr) of the purified component was found to be 72,000 by sedimentation and diffusion and 80,000 by SDS page using Mr reference standards. The properties of the immuno-suppressor strongly suggest that it is the secretory piece of dimeric IgA.

Efficient usage of a galactose-inducible expression vector for the production of heterologous protein in yeast.

We found that the expression vector previously constructed using the promoter of the GAL7 gene of Saccharomyces cerevisiae lacked the transcription terminator. The addition of the GAL7 terminator resulted in a more than 3-fold increase in the production of the protein encoded by cDNA of early region la (Ela) of human adenovirus, without affecting the amount of its mRNA. The positive regulatory gene, GAL4, when amplified with a vector of a high copy number, caused an about 5-fold increase in Ela production. We also found that medium containing a mixture of galactose and glucose can be used for the efficient production of the Ela protein.

Eliciting antibodies in chickens to human dimeric IgA. Removal of factors from human colostrum depressing anti IgA antibody production.

Contrary to expectation chickens did not readily elicit antibodies to IgA dimers when untreated human colostrum was used as antigen. When colostrum was fractionated by means of a column of 8% granulated agarose equilibrated with 10mM phosphate buffer, pH 7.2, a major and a minor fraction were obtained. The major or "1st fraction" consisted of two components with sedimentation coefficients of 10.9 S and 14.1 S, respectively. The minor or "2nd fraction" consisted of components of S values ranging from 2 to 6 and small amounts of 10.9 and 14.1 S material. When chickens were immunized with the "1st fraction" antibodies to dimeric IgA were produced. When the "1st and 2nd fractions" of the column were remixed and used for immunization of chickens, the immune response was as poor as when the chickens were injected with untreated colostrum. An immuno-depressing agent in colostrum was indicated. When rabbits were immunized with clarified human colostrum, antibodies against five antigens were elicited, one of the antigens being dimeric IgA. The immuno-depressing agent is therefore not universal. The purified agent suppressed antibody formation in chickens against the haemocyanin of Jasus lalandii. The "activity" is therefore not specific for IgA and the remaining four antigens in human colostrum. The purified component is a glyco-protein with a hexose content in excess of 10%. The derivatized sugars prepared from it were shown by gas liquid chromatography to be an equimolar mixture of galactose, mannose and fucose. The molecular weight (Mr) of the purified component was found to be 72,000 by sedimentation and diffusion and 80,000 by SDS page using Mr reference standards. The properties of the immuno-suppressor strongly suggest that it is the secretory piece of dimeric IgA.

Compartmentation of glucose 6-phosphate in hepatocytes

Rat hepatocytes were incubated with 14C-labelled hexoses, and the specific radioactivities of glucose 6-phosphate, glucose 1-phosphate and fructose 6-phosphate were determined. (1) When suspensions of freshly isolated hepatocytes were incubated with [14C]glucose, the specific radioactivities of glucose 1-phosphate and fructose 6-phosphate were severalfold higher than that of glucose 6-phosphate. The ratios of the specific radioactivities decreased with time of incubation. These relationships were also found when incubations were carried out with primary cultures of rat hepatocytes or with crude homogenates of hepatocytes, but not with isolated nuclei. (2) When cells were incubated with [14C]fructose, the ratios of the specific radioactivities were higher than with [14C]glucose, and also decreased with time. (3) Paired incubations were carried out with a mixture of galactose and fructose, with one or other sugar being labelled with 14C. The specific radioactivity of glucose released into the medium was greater than that of glucose 6-phosphate when fructose was labelled, but not when galactose was labelled. Furthermore, glucose 6-phosphate and glucose in the medium differed with regard to the distribution of 14C between C-1 and C-6. These results are interpreted as evidence that glucose 6-phosphate in hepatocytes does not exist as a homogeneous pool, but that subcompartments exist which are associated with glucose phosphorylation, gluconeogenesis and glycogenolysis.

A Rat Bioassay for Measuring the Comparative Availability of Carbohydrates and Its Application to Legume Foods, Pure Carbohydrates and Polyols

An assay was developed to evaluate the bioavailability of dietary carbohydrate by slope-ratio analysis of weight gain and plasma ketones of rats fed a carbohydrate-free diet supplemented with glucose as a standard and selected food items, pure carbohydrates and polyols. The diet was based on 35% food grade oleic acid, 12% casein protein supplemented with methionine (0.3%) and arginine (0.2%), 7.5% soybean oil, 37% cellulose, minerals and vitamins. Glucose, as the reference standard, or test materials were incorporated in the diet by replacing equi-energetic amounts of oleic acid and adjusting cellulose to equalize total weight. Optimal levels of protein (casein) and triglyceride (soybean oil) in the basal diet were defined as those levels above which additional protein or fat would serve only to provide endogenous glucose from their glucogenic amino acids and glycerol constituents. A standard dose-response curve was obtained by feeding diets containing 0%, 1% and 2% glucose. Similar dose response curves were obtained by feeding test materials. Under these experimental conditions, additional glucose or additional protein were growth stimulating and casein had approximately 50% of the value of an equal weight of glucose, which was consistent with its content of glucogenic amino acids. The specific carbohydrate value of a food was estimated in the assay by subtracting the calculated glucogenic value of its digestible protein from the total response. The apparent availability of the carbohydrates (i.e., nitrogen-free extract) in soybean meal, lima bean (Phaseolus lumatus), and chick pea (Cicer arietinum) were 35, 70, and 80%, respectively, as available as glucose. Galactose, a 1:1 mixture of galactose + glucose, fractose and starch were as available as glucose. Lactose, ribose, sorbitol, and xylitol were 50 to 65% as available as glucose while mannitol and inulin were not available to a significant extent. Possible metabolic bases for these differences are discussed.

Carbohydrate digestion and absorption studies in the horse

The ability of the horse to digest and absorb soluble carbohydrates was assessed using a series of oral disaccharide tolerance tests followed in the same animals by tolerance tests with the constituent monosaccharides. In horses older than three years, lactose did not produce an increase in the plasma glucose levels but induced the passing of soft faeces, indicating that adult horses are lactose intolerant. Horses of all ages could absorb the glucose: galactose mixture without any change in the faeces. The tolerance is due to a failure to hydrolyse lactose and does not involve the monosaccharide transport systems. These findings correspond to the known development pattern of brush border lactase activity in the equine small intestine. Both sucrose and maltose were rapidly hydrolysed, the resulting tolerance curves closely approximating to those for the constituent monosaccharides. Galactose was absorbed at a similar rate to glucose, although a dose of 1g/kg was necessary to produce galactosaemia. An oral lactose tolerance test (1 g/kg as a 20 per cent solution) could be of clinical value to determine small intestinal mucosal damage in diarrhoeic foals when the continued ingestion of lactose might be detrimental.

Collagen-mediated platelet aggregation. Effects of collagen modification involving the protein and carbohydrate moieties.

In an effort to elucidate the nature of the collagen-platelet interaction, the effects of collagen modification on platelet aggregation have been studied. We have shown that purified rat skin (salt) soluble collagen is effective at about 20 nM in mediating platelet aggregation in human platelet-rich plasma. This concentration is somewhat greater than that required of several skin insoluble collagens (ca. 10 nM). Both the alpha1(I) and alpha2 chains from rat skin soluble collagen produced platelet aggregation, but only at concentrations of about 13 muM and 55 muM, respectively. In contrast, heat-denatured collagen and chains (e.g., 65 muM alpha1(I) and 160 muM alpha2) failed to induce platelet aggregation and to inhibit platelet aggregation by native collagen. Glycopeptides were prepared from human skin insoluble collagen by extended digestion with bacterial collagenase and trypsin, and were purified by gel filtration into two classes. One class of higher molecular weight contained sialic acid, glucosamine, galactosamine, fucose, mannose, galactose, and glucose, and the other of lower molecular weight consisted primarily of a mixture of galactose and galactosyl-glucose units O-glycosidically linked to hydroxylysine-containing peptides. We found that, after the residual tryptic activity contaminating the higher molecular weight fraction was inhibited, neither of the glycopeptide classes produced nor inhibited native human skin insoluble collagen-mediated platelet aggregation at the highest concentration examined (ca. 1-2 mg glycopeptide per ml of platelet-rich plasma). Highly purified samples of the hydroxylysyl glycosides, hydroxylysylgalactose and hydroxylysylgalactosylglucose (Hyl-Gal and Hyl-Gal-Glc, respectively), were prepared from human urine and labeled at galactose using galactose oxidase followed by reduction with tritiated borohydride. Binding studies with platelet-rich plasma showed that, at concentrations greater than 50 nM, Hyl-Gal gives apparent binding to platelets, but there was no evidence of Hyl-Gal-Glc binding to platelets at concentrations up to 250 nM. At concentrations several hundredfold higher than the equivalents present in the minimum concentration of rat skin soluble collagen required for platelet aggregation, neither Hyl-Gal (at 29 muM) nor Hyl-Gal-Glc (at 18 muM) caused platelet aggregation or inhibited platelet aggregation by native collagen. Also, at a concentration of 85 muM (which represents a concentration about two thousandfold higher than the equivalents in the minimum concentration of soluble collagen required for platelet aggregation) the Gal-Glc-containing 36 residue rat skin soluble collagen alpha1(I)cyanogen bromide #5 peptide had no platelet aggregating or inhibiting activity. Modification of at least 90% of the rat skin soluble collagen carbohydrate by mild periodate oxidation had no effect on the platelet aggregating activity. Human skin insoluble collagen was reacted with periodate under the same conditions, and this had no demonstrable effect on its ability to induce platelet aggregation. This indicates that the normal carbohydrate side chains of these collagens are not required for the platelet interaction that produces the release of ADP and other metabolic constituents and leads to aggregation.Thus, collagen-platelet interactions appear to involve at least two distinct binding sites on the platelet plasma membrane. One is a protein binding site that activates platelet aggregation and has high specificity and affinity for the collagen triple-helical fold or perhaps even for a particular amino acid sequence in the triple helix.

Antitumor Agents from Agave schottii(Amaryllidaceae)

Extracts of Agave schottii Engelm. (Amaryllidaceae) were shown to be effective inhibitors of the Walker carcinoma 256 (intramuscular) tumor system of the CCNSC. The active material was shown to be saponin. By means of a Silica Gel G dry-column technique, an effective separation of the acetates of the saponins present was accomplished. Gitogenin was identified as the genin of all saponins present. While the sugar associated with the saponin showing the highest degree of activity was galactose, the sugars associated with the three other saponins were identified as a mixture of galactose and glucose.

Determination of galactosamine and N-acetylgalactosamine in the presence of other hexosamines with galactose oxidase

A specific method for the determination of galactosamine and N-acetylgalactosamine in the presence of other hexosamines is presented. The method is based on the action of galactose oxidase on these derivatives of galactose. By the use of an appropriate ion-exchange resin, an analysis of a mixture of galactose, galactosamine and N-acetylgalactosamine can also be carried out.

The bulk growth of animal cells in continuous suspension culture.

SUMMARY: Several methods for growing animal cells in suspension culture were examined, to find the most efficient in terms of cells produced in a given time for the minimum of medium and attention. Continuous medium flow was more efficient than batch-culture, and the preferred system was to add medium to a culture vessel regularly in small doses via a time-switch-controlled solenoid closure at a rate similar to the growth rate; a turbidimetric safety device ensured that cell density did not drop below levels permitting growth. A mixture of galactose or fructose (6 g./1.) and glucose (2 g./1.) allowed better pH control than glucose alone (6 g./1.). Doubling times of 14r–16 hr. were obtained on occasion; the gas-phase oxygen concentration for fastest growth depended on cell density and was frequently less than atmospheric, suggesting that these cells can behave as microaerophils.702

The influence of certain factors on the in vitro production of ergot alkaloids by Claviceps purpurea (Fr.) Tul.

Eighteen of 41 isolates of Clavkeps purpurea produced a detectable quantity of the ergot alkaloids under standard conditions. Large differences in yield indicated that strain differences existed. There was no correlation, however, between the capacity to produce alkaloids and either the species of host from which the culture was isolated or the pigmentation of the culture.The time of incubation and the composition of the medium were important in determining whether natural light stimulated or inhibited the synthesis or accumulation of ergot alkaloids.Commercial galactose, which was contaminated with glucose and lactose, was the most efficient carbon source examined, but the rate of synthesis was markedly reduced if the galactose was purified before use. The activity of commercial galactose could be replaced by a mixture of pure galactose and glucose but not by a mixture of galactose and lactose. A strong interaction existed between the concentration of commercial galactose and phosphate. Ammonium succinate, soybean meal, urea, and yeast extract were the most efficient nitrogen sources examined. L-Tryptophane could not serve as a nitrogen source for growth but when added as a supplement influenced alkaloid production. Succinic but not citric, tartaric, phosphoric, acetic, or sulphuric acid could be used successfully to adjust the initial pH of the production medium. The replacement culture technique did not shorten the incubation time required for alkaloid production.Production of alkaloid, growth, and consumption of carbon and nitrogen proceeded at a steady rate until the 43rd day when the rate decreased markedly. Organic nitrogen but not polysaccharide was secreted into the medium.The total yield and the rate of alkaloid synthesis was influenced by the size of the inoculum and by the nature of the agent used to suspend the inoculum, but not by the number of times the inoculum was washed. The rate of production was very slow if the inoculum source was not homogenized.

SEPARATION OF CARBOHYDRATES ON COCOANUT CHARCOAL COLUMNS

not available

THE RELATIVE SWEETNESS OF VARIOUS SWEET COMPOUNDS AND OF THEIR MIXTURES

Responses to specific sweet stimuli are specific for any one individual, but for that individual only. Comparisons as to degree of sweetness of different stimuli may vary from individual to individual. Rigid data are probably unattainable; it is only possible to determine the average opinions of a group of individuals.The following solutions were found to be equally sweet by the group of individuals employed:(i) 5.0% sucrose and 8.3% glucose; 10.0% sucrose and 14.4% glucose (which modified the figure previously found, after proper weighting, to 14.6%).(ii) 5.0% galactose and 2.5% sucrose; 10.0% galactose and 6.0% sucrose; 15.0% galactose and 10.0% sucrose.(iii) 5.0% mannitol and 2.47% sucrose; 10.0% mannitol and 5.54% sucrose; 15.0% mannitol and 9.8% sucrose.(iv) 2.0% sucrose arid 0.0049% 'soluble saccharine' (approximate only).(v) 0.0125% dulcine and 3.35% sucrose; 0.025% dulcine and 4.1% sucrose; 0.050% dulcine and 4.6% sucrose (all only approximate).(vi) 5.0% glycine and 3.25% sucrose; 30.0% glycine and 5.5% sucrose.(vii) 3.0% dl-alanine and 3.0% sucrose.While it has been shown earlier that the sweetnesses of sucrose and glucose, sucrose and lactose, glucose and lactose, sucrose and glycerol, and glucose and glycerol are additive when calculated in terms of glucose (but not in terms of sucrose), and it is now shown that this is true also for mixtures of galactose and glucose, and (probably) of dulcine and sucrose, this relationship does not hold for mixtures of glycine and sucrose, alanine and sucrose, and alanine and glycine. In such mixtures the total sweetness is less than that calculated in terms of glucose and usually less than when calculated in terms of sucrose.The relative sweetnesses of the group of compounds glucose, galactose, lactose, glycerol, and mannitol, compared with any one of them, do not change with concentration, within the limits of the experimental method used. On the other hand, the relative sweetnesses of these, and of fructose and dulcine, when compared with sucrose, change with concentration, the relationship being a log-log one. There is a similar log-log relationship when comparisons are made with fructose.A method is described for determining the value of iso-sweet iso-caloric mixtures of glucose and sucrose.A type curve can be constructed relating sweetness to concentration for glucose and the other compounds of its group. The relationship is log-log. A different log-log relationship between sweetness and concentration holds for sucrose.