Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.26 (invertase)
4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Leucrose [D-glucosyl-alpha(1----5)-D-fructopyranose] prepared by microbial-enzymatic transglycosidation from sucrose, is the first alpha(1----5)-linked disaccharide which possesses excellent nutritional properties with regard to metabolic utilization and is well tolerated. The aim of the present work was to assess its cariogenic potential. Yeast invertase was shown to be inhibited by leucrose in a noncompetitive way, while hydrogenated leucrose (leucritol) acted as an activator. Plaque polysaccharide forming glucosyltransferases from Streptococcus cricetus AHT were not influenced by leucrose, but by leucritol. Essentially no acid formation was observed after incubation of leucrose with suspensions of human dental plaque, S. mutans NCTC 10449, Lactobacillus casei LSB 132 and Actinomyces viscosus Ny 1 No. 30. Leucrose was a competitive inhibitor of the acid formation from sucrose by S. mutans NCTC 10449 at neutral pH. Furthermore, leucrose inhibited at neutral pH considerably the uptake of sucrose by S. mutans NCTC 10449. The uptake of fructose and maltose was also inhibited but that of glucose not at all. In Cara rats as the animal model, leucrose was compared to sucrose and to corn starch for its cariogenic potential. In sharp contrast to the group fed with 30% sucrose, caries scores of the 30% leucrose group were not significantly different from the starch group. pH telemetry with an indwelling electrode in man proved lueucrose to be 'safe for teeth' since plaque pH did not drop below pH 5.7. Leucrose is a novel noncariogenic disaccharide and thus represents a highly promising sugar substitute for caries prevention.
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PMID:Cariological assessment of leucrose [D-glucopyranosyl-alpha(1----5)-D-fructopyranose] as a sugar substitute. 250 93

Whole cells of Actinomyces naeslundii ATCC 12104, either in a dispersed form or in the form of plaque, enzymatically degraded sucrose to glucose and fructose. Washed whole cells expressed beta-fructofuranosidase specificity and hydrolyzed sucrose to essentially equimolar quantities of glucose and fructose. The cells readily hydrolyzed sucrose, raffinose, and Actinomyces viscosus or Aerobacter levanicum levan, but did not degrade melezitose, maltose, alpha-methyl-d-glucoside, melibiose, glucose-1-phosphate, or dextran T-500. Sucrose degradation occurred at a temperature optimum of 37 to 45 C and at a pH optimum of 5.7 to 6.0. The K(m) for sucrose was 0.05 M. Sucrose or raffinose in the growth medium resulted in cells with a specific activity that was fivefold greater than that of cells grown in medium supplemented with either glucose, fructose, maltose, lactose, or glucose and fructose, or grown in unsupplemented medium. Addition of sucrose to log-phase cells growing in glucose also increased the specific activity. Degradation of sucrose by whole cells in the form of plaque also occurred, but 6% less free fructose than free glucose was recovered. Sucrose-dependent synthesis of extracellular levan or glucan by whole cells or plaque could not be demonstrated. The ability of A. naeslundii to degrade sucrose and levan may be related to the pathogenic potential of this bacterium in plaque-associated oral diseases.
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PMID:Degradation of sucrose by whole cells and plaque of Actinomyces naeslundii. 461 24

The activity of enzymes releasing glucose and reducing sugars from sucrose, maltose, starch and dextran was compared in the same pooled samples of plaque fluid (PF) from 24 h human dental plaque. Equimolar amounts of glucose and fructose were released from sucrose in 3 h incubations. Reducing activity was released from sucrose or starch at a similar rate. The rate of glucose release from the starch substrate was similar to that from maltose but lower than that from sucrose. Raffinose was hydrolysed, indicating beta-fructosidase activity in PF. The hydrolysis of maltose, trehalose and melezitose confirmed the presence of alpha-glucosidase activity. Maltose was metabolized partially to a maltosaccharide. No dextranase activity was detectable in PF, and the soluble polymeric carbohydrate in PF was partially degraded by fungal dextranase. Starch was degraded to dextrins, maltose and glucose.
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PMID:Hydrolysis of some carbohydrate substrates by enzymes of pooled human dental plaque fluid. 617 18

Seven known alpha-glucosidase/beta-fructosidase inhibitors were examined for inhibitory effect against invertases in pooled human dental plaque. The inhibitors used were acarbose, Trestatin, nojirimycin, 1-deoxynojirimycin, glucono-delta-lactam, conduritol-B-epoxide, and Hoe 467A. Plaque homogenates were incubated with 14C-labelled sucrose and invertase activity was assayed by determination of radio-labelled monosaccharide after paper chromatography. Conduritol-B-epoxide, acarbose, and Trestatin reduced the invertase activity an average of 62%, 51%, and 35% respectively. The other inhibitors affected the enzyme activity negligibly. By combining conduritol-B-epoxide with acarbose or Trestatin in other plaque homogenates the inhibition of invertases increased from 35% to 61%. This observation supported the concept that the invertases in dental plaque consist of both alpha-glucosidases and beta-fructosidases.
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PMID:Effect of seven inhibitors on invertases in homogenates of human dental plaque. 622 87

A sample of human dental plaque was homogenized in transport fluid and inoculated simultaneously into a glucose-limited and a glucose-excess chemostat maintained at pH 7.0 and a dilution rate (D) of 0.05 h-1. In an attempt to ensure the establishment of slow-growing bacterial populations, two further inoculations of each chemostat with fresh samples of dental plaque took place before a steady-state was attained at this dilution rate. The dilution rate was increased step-wise to D = 0.6 h-1, and then returned directly to D = 0.05 h-1. Contrary to chemostat theory, microbial communities with a high species diversity were maintained under all of the experimental conditions employed, although not all of the bacterial populations present in the inocula established successfully in the chemostat. At each steady-state the bacteriological composition and biochemical properties (fermentation products, enzyme assays and acid production) of the communities of each chemostat was determined. Higher cell yields and a slightly more diverse community were obtained from the glucose-limited chemostat at all dilution rates. A complex mixture of end products of metabolism was obtained from the glucose-limited chemostat, suggesting amino acid catabolism, while lactate was the predominant acid of the glucose-excess culture. In washed-cell experiments, communities from the glucose-excess chemostat produced the lower terminal pH values following a pulse of glucose, with the lowest pH values occurring at the higher dilution rates. A film of micro-organisms, which accumulated around the neck of the chemostat, was sampled at the end of the experiment. The microbial composition of the films from each chemostat differed markedly, and both were different to the community of the bulk fluid of the respective chemostat. Spirochaetes and a population of yeasts were detected in the films from the glucose-limited and glucose-excess chemostats, respectively. No invertase or glucosyltransferase activity, and little glucoamylase-specific glycogen was detected in the communities from either chemostat, although significant endogenous activity, particularly at high dilution rates, was obtained with washed-cells from the glucose-excess chemostat. The results suggest that the chemostat could make a valuable contribution to the study of the ecology of dental plaque.
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PMID:The influence of growth rate and nutrient limitation on the microbial composition and biochemical properties of a mixed culture of oral bacteria grown in a chemostat. 634 8

20 reference strains and 72 isolated strains from dental plaque of streptococci, actinomyces, and lactobacilli species were examined for sucrase and maltase activities. The type of sucrase in the different strains was determined by use of the alpha-glucosidase inhibitor, acarbose. The enzyme activities were determined as formation of monosaccharide, and quantitated spectrophotometrically. Although variations occurred in enzyme activities between reference and isolated strains, the same general pattern was noticed. Strains of Streptococcus mutans and S. salivarius showed regularly the highest sucrase activities, followed by strains of Actinomyces viscosus and A. naeslundii. Most lactobacilli belonged to the bacteria with low sucrase activity like S. sanguis and S. mitior. In some lactobacilli strains, however, a high sucrase activity was observed. The level of sucrase activity in S. mutans strains was dependent on biotype/serotype, as strains of biotype V/serotype e showed high activities, biotypes I and IV corresponding to serotypes c, f, and d showed intermediate activity, and biotype III/serotype a always showed low activity. In most of the strains the sucrases were composed of enzymes with specificity against both alpha-glucosidic linkage and beta-fructosidic linkage of the sucrose molecule, but in varying ratios. In all species, exept S. sanguis and S. mitior, lower maltase than sucrase activity was observed, but even in the two species mentioned the maltase activities were relatively low. On the basis of observations of selected reference strains in every species examined both sucrases and maltases are to some extent inducible.
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PMID:Sucrase and maltase activities in supragingival dental plaque in humans of streptococcal, actinomyces and lactobacilli species. 637 64

The pathogenesis of diarrhea caused by rotavirus infection was studied in miniature swine piglets. The animals were inoculated orally with 2 X 10(7) plaque-forming units of porcine rotavirus (OSU strain). During the height of diarrhea, intestinal function was investigated by in vivo perfusion of a 30-cm segment of proximal jejunum and a 30-cm segment of distal ileum. Absorption of Na+ and water decreased and 3-O-methylglucose transport was markedly reduced, P less than 0.01 compared to control animals. Mucosal lactase and sucrase levels were depressed in both the jejunum and ileum, P less than 0.001. Na+,K+-ATPase activity was significantly depressed only in the ileum, P less than 0.001. These changes were associated with a marked reduction in villous height, suggesting that the diarrhea could be an osmotic diarrhea due to nutrient (carbohydrate) malabsorption. Fresh stool samples were obtained and analyzed immediately for NA+,K+, osmolarity, glucose, and lactose; the osmotic gap was also determined. Stool osmolarity continually increased from 248 +/- 20 mosm/liter prior to inoculation to 348 +/- 20 mosm/liter at 75 +/- 1 hr postinoculation (P less than 0.005); the majority of the fecal osmotic gap could be accounted for by the amount of lactose present in the stools. Stool sodium increased from 34 +/- 6 mM prior to inoculation to a maximum of 65 +/- 4 mM at 53 +/- 1 hr postinoculation, P less than 0.001. There was no significant change in potassium concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Pathogenesis of rotavirus-induced diarrhea. Preliminary studies in miniature swine piglet. 648 82

Inhibition of microbial enzymes in human dental plaque catalyzing the cleavage of the disaccharides maltose, sucrose and lactose was carried out with the alpha-glucosidase inhibitor, acarbose. The maltases from plaque homogenates were totally inhibited, whereas the inhibition of the invertases varied considerably. With increasing inhibitor concentrations, from 1 mM to 50 mM, the inhibition of the invertases increased. Preincubation for 30 min of the plaque homogenate with inhibitor resulted in a 20% increase of the inhibition of invertase activity. The inhibitor showed non-competitive inhibition of the invertases in the homogenates, whereas the maltases were competitively inhibited. The lactases were not inhibited at all. The invertases from human dental plaque may be alpha-glucosidases and/or beta-fructosidases.
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PMID:Effect of the alpha-glucosidase inhibitor, acarbose, on disaccharide splitting enzymes in human dental plaque. 680 51

Supragingival human dental plaque was collected from patients with evidence of caries. The plaque was frozen and stored at -20 degrees C. Pooled plaque was homogenized in acetate buffer pH 5.0 in an ice-water bath. By incubating the homogenate at pH 5.0 with [U-14C]-sucrose the formation of glucose and fructose was followed. Incubation in acetate buffer at pH 5.0 eliminated the glycosyltransferase activities and the glycolytic pathway. Normal Michaelis-Menten kinetics were observed until about 40 mM sucrose. At higher concentration of sucrose, excess substrate inhibition occurred. Storage of the homogenate at -20 degrees C resulted in decrease of the invertase activity with time.
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PMID:Method for determination of invertase activity in homogenates of human dental plaque. 695 Dec 45

Samples of 2-day plaque were collected before and during two 25-day diet periods from 24 subjects taking part in a double-blind cross-over study involving sucrose- and maltose-rich diets. The mean change in plaque pH measured after exposure to the respective sugar during the 3rd week of both diet periods was similar. The dry weight of plaque did not vary significantly as either diet progressed but the lowest mean value obtained was in the 4th week of the maltose diet. The extracellular polysaccharide content of plaque was lower in the maltose group than in the sucrose group (p = 0.052). Plaque-invertase activity was not affected significantly by the diets but maltase activity was significantly higher in the 2nd and 4th weeks of the maltose diet (p = 0.039; p = 0.012). The results suggest that the polysaccharide matrix of plaque formed in the presence of maltose as opposed to sucrose is different, which could be explained by the known effect of maltose in vitro on plaque glucosyl transferases.
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PMID:The influence of the replacement of dietary sucrose by maltose on the formation and biochemistry of human dental plaque. 695 74


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