Showing papers on "Sucrose published in 1975"

Aggregation states and catalytic properties of the multienzyme complex catalyzing the initial steps of pyrimidine biosynthesis in rat liver.

Abstract: Glutamine-dependent carbamoyl-phosphate synthetase was purified about 2100-fold from the cytosol of rat liver using 30% (v/v) dimethyl sulfoxide and 5% (w/v) glycerol as stabilizers. Throughout the purification, aspartate transcarbamylase and dihydroorotase, the second and third enzymes of pyrimidine biosynthesis, were copurified with the synthetase. These three enzymes sedimented as a single peak with a sedimentation coefficient of 27 S in sucrose gradients containing the stabilizers, indicating their existence as a multienzyme complex. The aggregation states of the complex were analyzed by sucrose gradient centrifugation under conditions approximating those used for enzymatic assay and correlated with the kinetic properties of the synthetase. In the presence of 10% glycerol and 10 mM MgATP(2-) at 18 degrees, the synthetase showed high activity and the three enzymes sedimented as a single peak with a coefficient of 25 S. The three enzymes also existed as a complex with the same coefficient when 50 muM PP-ribose-P was added in place of MgATP(2-), the sedimentation coefficient of the complex shifted to 28 S, indicating alteration in its molecular shape, rather than size. With 10% glycerol alone, the complex partially dissociated and the synthetase activity appeared in three peaks with coefficients of 26, 19, and 9 S (carbamoyl-phosphate synthetases (CPSase) a, b, and c, respectively). CPSases a, b, and c, thus obtained, were all sensitive to regulation by UTP and PP-ribose-P, but they differed MgATP(2-) (5.1, 4.8, AND 1.7 mM for CPSases a and b, and the enzyme within the original complex, respectively) and in their sensitivities to effectors. These results suggest that the aggregation may modify the catalytic and regulatory properties of the synthetase; Attempts to reassociate the components were unsuccessful.

The foliar and floral nectaries of turnera ulmifolia l.

Abstract: A B S T R A C T The floral and foliar nectaries of Turnera ulmifolia are specialized and are representative of others found in the Turneraceae. The foliar and floral nectary systems must be treated independently. Foliar nectaries are organized into a definite structure (composed of a base, rim, secretory tissue, modified epidermis) and are supplied with vascular tissue composed of both xylem and phloem. Nectar from foliar nectaries contained equal concentrations of glucose, fructose, and sucrose. Floral nectaries are an integral part of the basal portion of each filament. The nectariferous tissue is not supplied with vascular tissue and secretion lasts only a few hours. Nectar from these staminal nectaries yielded a sucrose-dominant nectar containing also fructose, glucose, an unknown, and a trace amount of melezitose. Observations of flowering confirmed the reported short duration of the individual flowers. CURRENT INTEREST in insect and plant interactions has led to many field-oriented projects. However, detailed studies of the morphology, anatomy, and analysis of the nectar are often lacking. Among the more interesting associations are those involving both floral and foliar nectaries on

Changes in the individual sugars of tomato fruit during ripening

Abstract: Changes in the concentrations of the individual sugars of the walls and locular contents of tomato fruit during ripening have been studied. The major sugars were glucose and fructose together with much smaller amounts of sucrose and myoinositol. During the initial stages of development the fruit contained approximately twice as much glucose as fructose, but with approaching maturity and the onset of ripening the glucose/fructose ratio declined to less than unity. On a per fruit basis the distribution of the major sugars between the walls and locular contents was about 3 : 1 at the green stage, falling to 2 : 1 as the fruit ripened. Total reducing sugars (% fresh weight or per fruit) increased markedly between the mature green and green-yellow stages with a tendency to decrease with subsequent ripening. These changes were predominantly influenced by changes in fructose content, with glucose changing little. The concentrations of sucrose and myoinositol, both less than 0.05% fresh weight, declined with ripening. The green areas of the outer walls of “blotchy” fruit contained much less glucose and fructose than did the walls of normal mature green fruit, while the red areas contained amounts similar to those encountered in normally ripened red fruit.

Germination of Botrytis cinerea conidia in vitro in relation to nutrient conditions on leaf surfaces

Abstract: Conidia of different isolates of Botrytis cinerea Pers. ex Fr. varied widely in ability to germinate in water. Sugars and amino acids were added at concentrations similar to natural levels on leaf surfaces. To a limited extent simple sugars promoted germination. Fructose was most effective whilst sucrose was least effective. Amino acids stimulated germination with the exception of taurine and lysine. Lysine reduced the stimulatory effect of a mixture of amino acids. Germination of conidia was only increased by an inorganic nitrogen source, ammonium salts or by a mixture of mineral salts, when glucose was present. Growth factors, yeast extract, gibberellic acid and kinetin had no effect on germination but indole-acetic acid caused a small stimulation. Abscisic acid depressed germination. It is suggested that, like soil fungi, the germination of spores of phylloplane fungi may be nutrient-dependent, or independent with respect to exogenous nutrients. Poor in vivo germination of B. cinerea may be associated with competition.

Movement of 14C-labeled Sugars into Kernels of Wheat (Triticum aestivum L.)

Abstract: An anatomical study of wheat (Triticum aestivum L.) kernels 14 days after anthesis revealed that the tracheary elements of the pericarp vascular bundle are not in direct continuity with those of the rachilla. The phloem was continuous from the rachilla into the crease of the pericarp.Shortly after exposure of the flag leaf to (14)CO(2), relatively high proportion of the (14)C extracted from the pericarp and endosperm was found in glucose and fructose. With additional time, the percentage of (14)C in the monosaccharides declined and that in sucrose increased to a maximum 3 hours after (14)CO(2) exposure. The monosaccharides comprised about one-half of the soluble sugars extracted from the pericarp. Based on these observations, it appeared that sucrose hydrolysis might be prerequisite to sugar movement from the terminal phloem elements in the pericarp and into the endosperm. However, when (14)C-fructosyl-sucrose was injected into the peduncle, there was little additional randomization of the (14)C between the glucose and fructose moieties of sucrose extracted from the pericarp and endosperm compared to the rachis sucrose. If we assume that injected sucose was transported to the kernels via the phloem, then either sucrose moves out of the terminal phloem elements in the pericarp and into the endosperm unaltered, or if hydrolysis and resynthesis are a prerequisite to transport into the endosperm, the products of hydrolysis are not freely available for isomerization.

Method for manufacture of {60 -galactosidase by microorganism

Abstract: When novel mold strains belonging to genus Absidia are cultured in an inducer-containing medium of the type ordinarily used for the culture of alpha -galactosidase producing molds, notably high alpha -galactosidase activity is produced and absolutely no invertase activity is produced in the mycelia. By treating beet molasses or beet juice with these mycelia, the yield of sucrose can easily be enhanced, since raffinose which is a substance impeding the crystallization of sucrose is effectively decomposed and sucrose is allowed to remain intact.

Carbohydrate composition of groundnuts (Arachis hypogea).

Abstract: The proximate composition of defatted edible groundnut flour, processed and unprocessed, has been determined. The flour contains about 38% total carbohydrates of which oligosaccharides account for 18%, starch 12.5%, hemicelluloses A and B 0.5 and 3.5% respectively and fibre (cellulose) 4.5%. Sucrose 13.90 and 14.55%, raffinose 0.89 and 0.92%, stachyose 1.56 and 1.60%, and verbascose 0.41 and 0.42% represent the oligosaccharide fractions (from 70% alcoholic extract) of unprocessed and processed flour, respectively. In addition the unprocessed flour also contained glucose 0.80% and fructose 0.41 % along with two unidentified spots 0.70%. Hemicellulose A consisted of glucose, arabinose, and xylose (4 : 0.5 : 0.1) whereas hemicellulose B had galacturonic acid, glucose, galactose, arabinose and xylose (1 : 4: 1 : 12 : 6). The fibre fraction on hydrolysis yielded predominantly glucose with only traces of galacturonic acid and rhamnose. The presence of verbascose and xylose in groundnuts has not been previously reported.

Effect of Sucrose Feeding on the Intestinal Transport of Sugars in Two Strains of Rats

Abstract: The rates of intestinal transport of dietary monosaccharides and disaccharides were determined in Wistar rats and the carbohydrate-sensitive BHE rats fed either a stock diet or a 65% sucrose diet. Sucrose-fed rats of both strains generally showed large and significant increases in the rates of glucose, alpha-methylglucose, fructose, and sucrose transport. The transport of galactose, maltose, and lactose did not show consistent increases due to sucrose feeding. Although the magnitude of the increases in sugar transport due to sucrose feeding was only slightly greater in BHE rats than in Wistar rats, BHE rats tended to exhibit a greater rate of sugar trnasport when fed both strains and in the BHE rats fed the stock diet. Lipogenic enzyme activity was greatly increased as a result of sucrose feeding; however, BHE rats did not show greater levels of enzyme activity than did Wistar rats. Liver lipids were increased in both the Wistar and the BHE sucrose-fed rats and in BHE rats fed either diet.

Heterotrophic growth of the filamentous blue-green alga Plectonema boryanum

Abstract: Plectonema boryanum can grow in the dark with ribose, sucrose, mannitol, maltose, glucose, or fructose. Cell doubling times with 10 mM substrate are the following: 5 days with ribose, 6 days with sucrose or mannitol, 10 days with maltose, 12 days with glucose, and 13 days with fructose; with ribose plus 0.1% casamino acids it is 2.5 days. Dark-grown cells appear morphologically similar to light-grown cells. Cells grown in the dark for several years remain pigmented and resume photoautotrophic growth when placed in the light. Dim light (85 lux) increases the growth rate with ribose and with ribose plus casamino acids to nearlytwice that of the dark rate. In moderate light, growth takes place with ribose even in the presence of 1x10-5 M DCMU.

Glucose, glucose-6-phosphate, lactate and pyruvate content of the retina, blood and liver of streptozotocin-diabetic rats fed sucrose- or starch-rich diets

Abstract: The feeding of starch- or sucrose-rich diets to normal rats for 20 days resulted in a significant increase in lactate level and L/P ratio in the retina in the sucrose-fed animals. There was no correlation between the glucose and lactate content of the blood and retina and it was concluded that the increased lactate content of the retina was derived from the fructose moiety of the sucrose. Liver hypertrophy occurred in both normal and diabetic animals fed the sucrose diet. When streptozotocin-diabetic rats were maintained for 20 days on the same diets significant increases in the lactic acid content of the blood and liver occurred, but the high level of lactate in the retina of the sucrose-fed normal rats was not further elevated. The feeding of sucrose to diabetic rats resulted in better metabolic control of both blood glucose and lactate as compared with the maintenance of these animals on a starch diet.

Demonstration of a specific metabolic effect of dietary disaccharides in the rat.

Abstract: Male Wistar rats were starved and refed diets containing either 40% carbohydrate as monosaccharides (glucose, fructose, invert sugar) or disaccharides (maltose, sucrose), or 422% carbohydrate as glucose Induction of various liver enzymes and changes in total liver lipid levels by the different dietary sugars were studied Liver enzymes measured included glucose-6-phosphate dehydrogenase (g6pd), 6-phosphogluconate dehydrogenase (6PGD), malic enzyme (ME), phosphofructokinase (PFK), L-alpha-glycerol phosphate dehydrogenase (LalphaGPD), pyruvate kinase (PK), citrate cleavage enzyme (CCE), acetyl CoA carboxylase (AcCoAC), and fatty acid synthetase (FAS) The responses in enzyme activity to diets containing glucose or invert sugar were used as the basal response Enzyme responses to refeeding the carbohydrate diets fell into three categories: (1) enzyme activity increased both by the disaccharide configuration of the carbohydrate and by fructose (G6PD, PK, CCE, AcCoAC, FAS); (2) enzyme activity increased only by the disaccharide configuration of the carbohydrate (6PGD, ME); and (3) enzyme activity increased only by fructose (PFK, LalphaGPD) Total liver lipid level was increased both by the disaccharide configuration of the carbohydrate and by fructose Refeeding diets containing equal molar amounts of glucose or maltose did not abolish the disaccharide effect The data indicate that the disaccharide configuration of maltose and sucrose may have an effect at the gastrointestinal level, which causes an increased induction of certain enzymes in the liver

Identification and quantitative analysis of sugars and non-volatile organic acids in Chinese gooseberry fruit (Actinidia chinensis Planch.)

Abstract: The free sugars and non-volatile organic acids in Chinese gooseberry fruit were extracted and separated by lead salt and ion-exchange procedures. Sugars and acids were identified and quantitatively determined by gas-liquid chromatography (g.l.c.) of their trimethylsilyl (TMS) derivatives. Glucose, fructose, sucrose and trace amounts of sorbitol accounted for the total sugars. Citric, quinic and malic are the major acids, the outstanding feature being the high content of quinic acid in mature fruit. Small amounts of phosphoric, ascorbic, glucuronic, galacturonic, oxalic, succinic, fumaric, oxalacetic and p-coumaric acids are also present. Qualitative and quantitative analysis of acids prepared as lead salts agreed closely with the determination of acids isolated by the ion-exchange procedure. Identifications of sugars and acids were confirmed by paper and thin-layer chromatography. Reducing sugars, total sugars and titratable acidity were determined by AOAC methods and the results compared with those from g.l.c.

Inhibition of sucrase by tris in rat and man, demonstrated by oral loading tests with sucrose.

Abstract: In the course of work concerned with the inhibition of small intestinal carbohydrate digesting enzymes, experiments were performed on rats and two healthy volunteers using tris as a sucrase inhibitor. The following results were obtained: (1) Tris does not lower the blood glucose in fasting rats after oral or subcutaneous doses up to 500 mg/kg, when administered as neutral solution (pH 7.0). (2) Tris reduces the glycemia in rats and human subjects after a sucrose load. In addition, the insulinemia caused by administration of sucrose is reduced in man. This smoothing effect on both curves is dose-dependent. A delay of gastric emptying by tris could be excluded. (3) After a glucose or maltose load in rats, tris has no effect on the blood sugar curve. (4) The marked smoothing effect of tris after sucrose loading is probably caused by its well-known in vitro inhibitory effect on intestinal sucrase activity of pigs and humans.

Effects of Carbon Dioxide on Metabolism by the Glycollate Pathway in Leaves

Abstract: When solutions of [14C]glycollate, glycine, serine, glycerate, or glucose were supplied to segments of wheat leaves through their cut bases in the light, most of the 14C was incorporated into sucrose in air but in C02-free air less sucrose was made. The synthesis of sucrose was decreased because metabolism of serine was partly blocked. Sucrose synthesis from glucose and glycerate in C02-free air was decreased but to a smaller extent ; relatively more CO2 was evolved and serine accumulated. The effects of DCMU and light of different wavelengths on metabolism by leaves of L-[U-14C]serine confirmed that simultaneous photosynthetic assimilation of carbon was necessary for the conversion of serine to sucrose. Of various products of photosynthesis fed exogenously to the leaves a-keto acids were the most effective in promoting photosynthesis of sucrose and release of 14C02 from 14C-labelled serine. This suggests that in C02-free air the metabolism of serine may be limited by a shortage of a-keto acid acceptors for the amino group. In C02-free air added glucose stimulated production of CO2 and sucrose from d-[U-14C] glycerate and no competitive effects were evident even though glucose is converted rapidly to sucrose under these conditions. In addition to a supply of keto acid, photosynthesis may also provide substrates that can be degraded and provide energy in the cytoplasm for the conversion of glycerate to sugar and phosphates and sucrose.

Effects of Dietary Sucrose Levels on Extracellular Polysaccharide Metabolism of Human Dental Plaque

Abstract: The effects of increased and low dietary sucrose levels on the biochemical activities and composition of 4- and 12-day plaque were investigated in eight young men. The subjects were fed supervised, nutritionally adequate diets. Dextran hydrolase, levan hydrolase, and total carbohydrate content were increased during a sucrose-rich diet while invertase activity was decreased. Base-extractable carbohydrate was decreased in four-day plaque during the sucrose-rich diet. Glucosyltransferase and fructosyltransferase activity, buffer-soluble carbohydrate, and buffer-soluble protein were also determined.

Method for manufacture of α-galactosidase by microorganism

Abstract: When novel mold strains belonging to genus Absidia are cultured in an inducer-containing medium of the type ordinarily used for the culture of α-galactosidase producing molds, notably high α-galactosidase activity is produced and absolutely no invertase activity is produced in the mycelia. By treating beet molasses or beet juice with these mycelia, the yield of sucrose can easily be enhanced, since raffinose which is a substance impeding the crystallization of sucrose is effectively decomposed and sucrose is allowed to remain intact.

A Study on the Influence of Drying Methods upon the Chemical Changes in Red Pepper - 2. Changes of Free amino acid, Free sugar -

Abstract: This investigation was designed to determine the influence of drying methods on the free amino acids and free sugars in red pepper and to study the browning mechanism of brown-colored red pepper. Three different drying methods were employed: 1) Sun-drying at for 15 days, 2) Drying in oven at for 49 hours, and 3) Drying in oven at for 8 hours. Dried and ground peels were used for the analysis of free amino acids and free sugars. The results were as follows; 1. Sixteen kinds of amino acids i.e. asparagine, methionine, and cystine etc. were identified. Total amino acid content of the sun-dried sample was not different from that of the fresh sample, but the samples dried at and in the oven were decreased to 24.9% and 67.4% respectively. Of amino acids identified, methionine, lysine and aspartic acid were decreased in all treatments. Especially, methionine ana aspartic acid were decreased rapidly to 71.8% and 73.3% , respectively. 2. Three kinds of free sugars i.e. glucose, fructose and sucrose were identified. The total content of free sugars was significantly decreased in each treatment. Among the reducing sugars, glucose was rapidly decreased; 65.9% for the glucose of sample dried at in the oven. 3. At the higher drying temperature, the darker red color was found. Brown-color appeared at showed appreciable losses in carotenoid content, but the major color seems to be due to the large increase in browning compounds. 4. It was assumed that increased browning compounds of red pepper were due to the Maillard reaction which is a nonenzymatic browning process.

Analysis of growth rate in sucrose-supplemented cultures of Streptococcus mutans.

Abstract: In the presence of sucrose, Streptococcus mutans grows in large glucan-containing aggregates. Because of reports of linear rather than exponential growth of sucrose-grown cultures, the kinetics of growth of sucrose-grown cultures of S. mutans strain OMZ-176 were compared with those of glucose-grown cultures. Culture turbidity measurements indicated that growth of sucrose cultures was slower, did not follow exponential kinetics, and slowed and stopped at lower absorbance values than did glucose-grown cultures. However, measurements of the rates of accumulation of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein using fully equilibrated radioactively labeled precursors of each of these macromolecular species in sucrose and glucose-grown cultures showed that: (i) for glucose cultures the synthesis of each of the three informational molecules occurred at the same exponential rate, which was identical to the rate of turbidity increase; (ii) for sucrose cultures each macromolecular species was synthesized at the same exponential rate and these rates were identical to the rate of increase of turbidity of the glucose-grown culture for periods of up to 7 h. Furthermore, the ratios of DNA to RNA, RNA to protein, and protein to DNA for the sucrose cultures were identical to those for the glucose cultures for up to 10 doublings. From these data it was concluded that in the presence of sucrose S. mutans grows in a balanced fashion at the same exponential rate as it does in glucose. The deviation from an exponential growth model of the absorbance in sucrose cultures was attributed to an optical artifact due to the formation of large glucan-containing aggregates of cells. The addition of dextranase to sucrose cultures resulted in cultures which increased in turbidity at the same exponential rate as glucose-grown cultures, without affecting the rate or extent of macromolecular synthesis.

Some metabolic effects of prolonged feeding of starch, sucrose, fructose and carbohydrate-free diet in the rat.

Abstract: Male rats of the ASL Wistar strain were fed from weaning on starch, fructose or carbohydrate-free diets for 4 and 12 weeks. In addition, further groups were fed for 24 weeks on starch, sucrose or carbohydrate-free diets. Livers were examined for gross composition, glucose-6-phosphatase activity and in vitro lipogenesis and glucose oxidation. Intestinal sucrase was also measured. Dietary fructose and the carbohydrate-free diet induced an enlargement of the livers after 12 weeks feeding, when expressed per 100g body weight, and at the same time, an increased fat content. Fructose caused an increase in liver glucose-6-phosphatase after 4 weeks, which persisted after 12 weeks, and a similar increase was observed after 24 weeks feeding on sucrose. Fructose produced an increase in intestinal sucrose after 4 weeks, but this did not persist and there was no increase evident after 12 weeks feeding, nor after 24 weeks feeding on sucrose. Fructose markedly depressed the in vitro lipogenesis and glucose oxidation in liver slices. This was evident after 4 weeks feeding and also after 12 weeks when the effect of age showed as a fall in both these parameters in the control group of animals. The carbohydrate-free diet caused an increase in liver glucose-6-phosphatase after 4 weeks, a smaller increase after 12 weeks, and there was no increase apparent when feeding was continued for 24 weeks. Apparently due to the absence of substrate, the intestinal sucrose activity fell to less than half after 4 weeks and to negligible levels after 12 and 24 weeks on carbohydrate-free diet. In vitro liver lipogenesis and glucose oxidation were depressed after 4 and 12 weeks in a similar way to the fructose diet. On both these diets the rise in liver glucose-6-phosphatase appeared to parallel the fall in liver lipogeneis and glucose oxidation.

The immediate effect of gamma irradiation upon the sugar content of potatoes previously stored at 2, 4.5, 6, 10 and 15.5°C

Abstract: The sugar content of samples of potatoes, cv. Majestic, was varied by storage for 4 weeks at 2, 4.5, 6, 10 and 15.5°C, before irradiation with 10 krad. With initial sucrose contents of 0.14–0.37% FW (tubers from 4.5–15.5°C) the marked temporary increase in sucrose, as reported previously, was observed, reaching a maximum after 3–7 days before falling rapidly to a level rather higher than in non-irradiated tubers. Tubers from 2°C, with 1.4% sucrose, showed an immediate drop in this after irradiation, succeeded within 3 days by a rise to values not significantly different from the controls. Irradiation caused a significant increase in reducing sugar content, for a period of up to 7 days in sweetened tubers, but for 21 days or more in unsweetened tubers. Previous storage at the different temperatures had some permanent residual effect upon the sugar content of the controls during subsequent storage for up to 90 days at 10°C.