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At least 19 recordsLinked to original sources
PubMed1977

Intravenous infusion of a dextrin, Caloreen, in human subjects: metabolic studies.

1. Caloreen, a glucose-polymer dextrin infused into human volunteers, although producing a clear increase in total plasma carbohydrate did not produce a satisfactory increase in plasma glucose levels or serum insulin levels. 2. Urinary losses were high and although small fragments of the dextrin (suggesting metabolic breakdown of the dextrin) were demonstrated in the urine, no suppression of plasma free fatty acid, glucagon or immediate increase in the respiratory quotient were noted, suggesting that the metabolism is too slow to make it useful for parenteral nutrition in its present form. 3. A dextrin with fewer branch-links might be more suitable.

Adult↗
PubMed1975

Structures of multi-branched dextrins produced by saccharifyiing alpha-amylase from starch.

From the digest of beta-limit dextrin (prepared from glutinous rice starch) with saccharifying alpha-amylase of Bacillus subtilis [EC 3.2.1.1] (BSA), two extensibely branched dextrins consisting of nine (No. 6, Fig. 1) and ten (No 7, Fig.1) glucose units were isolated by paper chromatography. Structural analysis using various enzymes revealed that No. 6 and No. 7 were both mixtures of four triply branched dextrins. They had structures which were built up with 63-alpha-glucosylmaltotriose and/or 62-alpha-glucosylmaltose as a linking unit. However, the branching configuration and the minimum alpha-1, 4-glucosidic linkages existing between two branches followed one of the three structures shown below: (see article).

Amylases↗
PubMed1975

Elimination of precipitates in oil red O fat stain by adding dextrin.

Addition of dextrin in the final 60% isopropanol of the Lillie-Ashburn super-saturated oil red O isopropanol technic moderately intensified the stain and decreased our required staining interval. Precipitates were decreased and the diluted solution remained usable into the second week. A saturated 60% isopropanol oil red O solution contained 33 mg/100 ml. Without dextrin the fresh supersaturated solution contains 40 mg, after 3 days 25 mg. With dextrin the fresh solution contained 130 mg dye, the 10-day-old one 100 mg/100 ml.

1-Propanol↗
PubMed1977

Production of Schardinger beta-dextrin by soluble and immobilized cyclodextrin glycosyltransferase of an alkalophilic Bacillus sp.

Succinylated cyclodextrin glycosyltransferase (EC 3.2.1.19) of an alkalophilic Bacillus sp. was adsorbed on a vinylpyridine copolymer. The enzyme had about 25% of the activity of soluble enzyme added. No increase of pH or thermal stability of the enzyme was observed by the adsorption, whereas optimum temperature for the enzyme action was shifted from 50 to 55 degrees C. The enzyme converted starch to cyclodextrine without significant loss of activity under the conditions of 4 times reusing of 6 hr conversion by the batch system or 2 weeks continuous reaction by the column system at 55 degrees C and pH 8.0. About 46% of the potato starch solution [15% (w/v)] was converted to cyclodextrins by the enzyme, and 52% was converted by the simultaneous action of the enzyme and alkaline pullulanase of alkalophilic Bacillus sp. (No. 202-1). These values were almost the same as those obtained by the soluble enzyme or enzymes system.

Bacillus↗
PubMed1979

Starch metabolism in Pseudomonas stutzeri. II. Purification and properties of a dextrin glycosyl-transferase (D-enzyme) and amylomaltase.

Amylomaltase and disproportionating enzyme (D-enzyme) were purified to homogeneity from cell-free extracts of Pseudomonas stutzeri using a six-step procedure. The presence of both glycosyltransferases in the same organism has not been reported before. Molecular weight determination by gel chromatography gave a value of 74,000 for the amylomaltase and 115 000 for the D-enzyme. Two subunits of different molecular weight were found in each enzyme as proved by sodium dodecyl sulfate-gel electrophoresis. The optimum pH of amylomaltase and D-enzyme activity is 7.6--7.7. Action of both glycosyltransferases on different maltodextrins showed that amylomaltase is most active with maltotetraose, and the Km value for this substrate is 7.1 mM. D-Enzyme catalyzed glucose release from maltose (Km = 8.3 mM) at a higher rate than from maltotriose and maltotetraose. With maltotriose as initial substrate, D-enzyme forms glucose, maltopentaose, maltoheptaose, maltononaose, maltoundecaose as major products. Amylomaltase acts on maltotriose, maltotetraose, and maltopentaose to form a series of homologous 1,4-alpha-glucans. No essential chain-lengthening reaction occurred with maltohexaose.

Glucans↗
PubMed1976

Starch degradation by the mould Trichoderma viride. II. Regulation of enzyme synthesis.

The synthesis of amylolytic enzymes by the maltose not-utilizing Trichoderma viride strain CBS 354.44 requires the presence of starch or dextrins. Several readily utilizable carbon sources such as glucose and glutamic acid were shown to exert a strong catabolite repression which completely inhibited enzyme induction by starch or dextrins. Enzyme synthesis occurs in the exponential and in the stationary growth phase. In the latter, the ratio between saccharifying and dextrinizing enzyme activity is invariably high. In the exponential growth phase this ratio depends on the nature of the inducing substrate. Growth on starch results in an initially high production of dextrinizing activity, the saccharifying one becoming predominant in the course of exponential growth. The latter activity in dextrin DE 30 cultures is predominant from the very beginning. Thus, the amylolytic enzyme system of T. viride consists of at least two different enzymes, the synthesis of each being controlled specifically. The careful regulation of the synthesis of the dextrinizing enzyme is discussed with special reference to the production of non-utilizable maltose by the latter.

Amylases↗
PubMed1975

Concerted action of beta-glucuronidase and beta-acetylglucosaminidase on hyaluronodextrins.

A kinetic analysis of the stepwise alternating action of beta-glucuronidase and beta-acetylglucosaminidase on oligosaccharides and dextrins derived from hyaluronic acid was undertaken, for better definition of the contribution of this process to hyaluronate catabolism. Production of monosaccharide from larger dextrins by action of either enzyme is powerfully inhibited by electrolyts. In the study, as in mammalian tissues, beta-glucuronidase is present in excess so that the concentration of beta-acetylglucosaminidase is rate controlling in the action on dextrin substrates. For this action, Vmax shows limited variation with ionic strength or molecular weight of substrate. At ionic strength 0.03, but not 0.18, Km decreases some 100-fold for increase of molecular weight from 2,000 to 15,000. It is specifically this decrease in Km that accounts for the prominent electrolyte inhibition observed with larger dextrins. The extremely low values of Km are attributed to multiple ionic enzyme-substrate interactions at sites remote from the catalytic center. The previously reported stimulation by electrolyte of the action of beta-glucuronidase and beta-acetylglucosaminidase on aryl glycosides, studied briefly, is apparently unrelated to the electrolyte effects seen with dextrins. The catabolic contribution of beta-glucuronidase and beta-acetylglucosaminidase appears to be restricted to hydrolysis of the smaller oligosaccharides produced by action of hyaluronidase, since, for any reasonable assumptions regarding cellular environment, the extent of their action on polymeric hyaluronate or larger dextrins must be limited.

Acetylglucosaminidase↗
PubMed1977

The action pattern of human salivary alpha-amylase in the vicinity of the branch points of amylopectin.

Salivary alpha-amylase hydrolyses amylopectin in stages. At the end of the so-called second stage, there are present glucose, maltose, and a series of alpha-limit dextrins containing (1 leads to 4)- and (1 leads to 6)-alpha-D-glucosidic bonds. The structures of the limit dextrins containing a single (1 leads to 6)-bond were examined. Six such dextrins were found. Of these, two were capable of being further hydrolysed by alpha-amylase, whereas the remaining four were true, amylase-resistant alpha-limit dextrins. The structures of the limit dextrins afforded information about those (1 leads to 4)-alpha-D-glucosidic bonds of amylopectin that are capable of being cleaved by salivary alpha-amylase and those that are resistant. In order to define further the action of alpha-amylase, the alpha-amylolytic products of 6-alpha-maltotriosyl-D-glucose, 6(3)-alpha-maltotriosylmaltotriose, and 6(3)-alpha-maltotriosylmaltotetraose were examined.

Amylases↗
PubMed1976

Starch degradation by the mould Trichoderma viride. I. The mechanism of starch degradation.

The mechanism of starch degradation by the fungus Trichoderma viride was studied in strain CBS 354.44, which utilizes glucose, starch and dextrins but is unable to assimilate maltose. It was shown that the amylolytic enzyme system is completely extracellular, equally well induced by starch, amylose or amylopectin and that it consists mainly of enzymes of the glucoamylase type which yield glucose as the main product of starch hydrolysis. Small amounts of alpha-amylase are produced also. The enzymes produced in starch cultures degrade starch, amylose and amylopectin equally well. Enzyme synthesis in starch media takes place to a considerable extent after exhaustion of the carbon source when maximum growth has been attained. Low-molecular dextrins are degraded by extracellular enzymes of the glucoamylase type. These enzymes are produced in media containing starch or dextrins. Maltotriose is consumed for only one third leaving maltose in the culture filtrate. Maltose is hardly attacked and hardly induces any amylolytic enzyme activity. No stable alpha-glucosidase appears to be produced.

Amylases↗
PubMed1976

The limit dextrinase from malted sorghum (Sorghum vulgare).

A limit dextrinase, free from contaminating carbohydrases, has been purified from malted sorghum flour. The enzyme readily hydrolysed alpha-limit dextrins having maltosyl or maltotriosyl side-chains, pullulan, and amylopectin beta-limit dextrin. Glycogen beta-limit dextrin and amylopectin were more slowly hydrolysed, the detection of the hydrolysis of amylopectin being dependent on enzyme concentration. No significant debranching of glycogen could be detected.

Chelating Agents↗
PubMed1975

Purification and some properties of a novel maltohexaose-producing exo-amylase from Aerobacter aerogenes.

Maltohexaose producing amylase (EC 3.2.1.-) is the fourth known exo-amylase, the three previously known being glucoamylase, beta-amylase and Pseudomonas stutzeri maltotetraose producing amylase. The enzyme after release from Aerobacter aerogenes cells by 0.1% sodium lauryl sulfate extraction was purified by ammonium sulfate precipitation, DEAE-Sephadex column chromatography and Sephadex G-100 gel filtration to 80-fold of the original sodium lauryl sulfate extract activity, It gave a single band on disc electrophoresis, and the molecular weight by gel filtration was 54 000. This amylase showed maximal activity at 50 degrees C and pH 6.80. The pH stability range was relatively wide, the enzyme retaining more than 90% of its initial activity in the range of 6.50-9.0. 80% of the activity was retained after 15 min at 50 degrees C. This enzyme produced maltohexaose from starch, amylose and amylopectin by exo-attack, but did not act on alpha- or beta-cyclodextrin, pullulan or maltohexaitol. Also the enzyme acted on beta-limit dextrins of amylopectin and glycogen to form branched oligosaccharides. The unusual reaction of this enzyme on beta-limit dextrin is discussed from the standpoint of the stereochemistry of 1,4-alpha- and 1,6-alpha-glucosidic bonds. This is the anomalous amylase for which it is recognized that 1,6-alpha-glucosidic linkages in the substrates can mimic the effect of 1,4-alpha-bonds, as previously observed in pseudo-priming reactions of E. coli phosphorylase.

Amylases↗
PubMed1978

Biosynthesis of glycogen in Neurospora crassa. Purification and properties of the UDPglucose:glycogen 4-alpha-glucosyltransferase.

The Neurospora crassa glycogen synthase (UDPglucose:glycogen 4-alpha-glucosyltransferase, EC 2.4.1.11) was purified to electrophoretic homogeneity by a procedure involving ultracentrifugation, DEAE-cellulose column chromatography, (NH4)2SO4 fractionation and 3-aminopropyl-Sepharose column chromatography. The final purified enzyme preparation was almost entirely dependent on glucose-6-P and had a specific activity of 6.9 units per mg of protein. The subunit molecular weight of the glycogen synthase was determined by electrophoresis in sodium dodecyl sulfate-polyacrylamide gel to be 88 000--90 000. The native enzyme was shown to have a molecular weight of 270 000 as determined by sucrose density gradient centrifugation. Thus, the glucose-6-P-dependent form of the N. crassa glycogen synthase can exist as trimer of the subunit. Limited proteolysis with trypsin or chymotrypsin converted the glucose-6-P-dependent form of the enzyme into an apparent glucose-6-P-independent form. The enzyme was shown to catalyze transfer of glucose from UDPglucose to glycogen as well as to its phosphorylase limit dextrin, but not to its beta-amylase limit dextrin. Moreover, glucose, maltose and maltotriose were not active as acceptors.

Cations, Divalent↗
PubMed1978

Synergistic effects of dietary carbohydrate and cholesterol on serum lipids and lipoproteins in squirrel and spider monkeys.

Serum lipid and lipoprotein responses to diets with a high level of simple carbohydrate (69% w/w sucrose) and a low level of saturated fat (5% w/w butter-coconut oil, polyunsaturated/saturated fatty acid ratio 0.03) containing 0, 0.1, and 1.0 mg/kcal added cholesterol was studied in five squirrel (Saimiri sciurea) monkeys. Variations in response produced by altering the nature of dietary carbohydrate (sucrose versus dextrin) and the fat (polyunsaturated/saturated fatty acid ratio, 0.03 versus 1.5) in the above diets were studied in three groups (five per group) of spider monkeys (Ateles sp.). In the absence of exogenous cholesterol, feeding a sucrose-saturated fat diet for 6 weeks produced a consistent increase in serum cholesterol in both species and an increase in serum triglycerides only in squirrel monkeys. Exogenous cholesterol had a remarkable synergistic effect on the high carbohydrate diet in increasing the serum cholesterol and had a suppressing effect on serum triglycerides in both species. Polyunsaturated fat reduced the hypercholesterolemic effect of sucrose with or without exogenous cholesterol. Dextrin diets resulted in lower serum cholesterol responses than sucrose diets when the diets contained 0 or 0.1 mg/kcal added cholesterol. Serum cholesterol response was reflected in beta- and alpha-lipoproteins. These results emphasize the varied response of serum lipids and lipoproteins to dietary changes in carbohydrate, fat, and cholesterol that might have a bearing on experimental atherosclerosis.

Animals↗
PubMed1977

Increased spore yields of Clostridium perfringens in the presence of methylxanthines.

The methylxanthines caffeine, theophylline, and isobutylmethylxanthine greatly increased spore yields of Clostridium perfringens strains FD-1, PS52, and PS49 when grown on Duncan-Strong medium or on a new casein-digest medium. Four other strains (KA3, and National Collection of Type Cultures strains 8798, 8238, and 10240) failed to show any significant increase when tested under similar conditions. The degree of sporulation increase was influenced by the carbohydrate energy source in some strains but not in others. Strain PS52 showed a large increase in spore yield when dextrin was the energy source but only a slight increase when raffinose served as the energy source. Strain FD-1 showed similar increases in spore yield with either dextrin or raffinose.

Caffeine↗
PubMed1977

Effect of dietary carbohydrates on intestinal transport and accumulation of 59Fe++ in iron deficients rats.

Laboratory rats were fed several types of carbohydrates incorporated into iron-deficient diets. The lowest active transport of 59Fe++ across the intestinal wall as well as the lowest intestinal accumulation of radioiron occurred in rats fed either dextrin or fructose, while rats fed cornstarch, sucrose, or sucrose plus lactose exhibited the highest active transport and the highest accumulation of radioiron in the intestinal tissue. Animals which received dextrin as the dietary carbohydrate also maintained the highest hematocrit and hemoglobin levels during the iron depletion period.

Animals↗
PubMed1976

Pilot plant production of glucose with glucoamylase immobilized to porous silica.

Glucoamylase was immobilized to porous silica and its kinetics and stability were observed with acid- and alpha-amylase-hydrolyzed dextrin as feed. The enzyme was found to be extremely stable in both laboratory and pilot plant operations. When the feed had been previously only lightly hydrolyzed, pore diffusion limitation caused appreciable decreases in glucose production rate. The severity of starch hydrolysis to dextrin markedly affected ultimate glucose yields. The diffusional gradients present in the carrier pores caused the immobilized enzyme to yield lower glucose concentrations than the free enzyme at similar feed conditions.

Glucose↗