Effect Of Glucose Oxidase Research Articles

Effect of glucose oxidase, transglutaminase, and pentosanase on wheat proteins: Relationship with dough properties and bread-making quality

Glucose oxidase (Gox), transglutaminase (TG), and pentosanase (Pn) were investigated for their effect on bread quality. The changes introduced in wheat protein by the action of these enzymes were analysed to explain dough behaviour. Gox treatment decreased free sulphydryl groups ( SHf), increased glutenin macropolymer contents, and modified the electrophoretic pattern of protein fractions. Gox modified mainly albumin, globulin, and glutenin, forming large protein aggregates. These modifications explained the high strength of the dough and the low bread specific volume of samples with Gox. TG treatment modified solubility in SDS of protein and decreased glutenin macropolymer content. However, it formed large protein aggregates. The new cross-linking bonds introduced by this enzyme were different to S–S bonds and, consequently, the dough was less extensible and showed high resistance. Pn treatment increased water soluble pentosan content. Moreover, in these samples a tendency to increase SHf content was observed. In addition, Pn increased protein solubility in isopropanol, which indicates that the reduction of pentosans size decreases steric impediment of insoluble pentosans, thus increasing interaction among protein and making their extraction easier. These changes at the microscopic level allowed explaining the formation of softer dough and the production of higher specific volume in breads with Pn.

EFFECTS OF GLUCOSE OXIDASE, HEMICELLULASE AND ASCORBIC ACID ON DOUGH AND BREAD QUALITY

ABSTRACT In this study, glucose oxidase alone or its combinations with hemicellulase or ascorbic acid were used in bread making. Glucose oxidase alone mainly decreased dough extensibility. It produced stiffer and less extensible dough. Combinations of glucose oxidase–hemicellulase presented lower extensibility and were more resistant to extension than glucose oxidase alone. When glucose oxidase–ascorbic acid combinations were used, the softening degree significantly decreased, regardless when added the lowest glucose oxidase in combination with ascorbic acid. Glucose oxidase–ascorbic acid combinations significantly modified dough resistance. The glucose oxidase alone significantly increased specific loaf volume. The Dallman value of loaves made with glucose oxidase alone was found higher than for control. The most dramatic effect of additives on specific loaf volume was observed when glucose oxidase–hemicellulase combinations were added. This effect has been ascribed to redistribution of water from the hemicellulose to gluten, which would render the gluten more extensible. Specific loaf volume showed a significant enhancement when glucose oxidase–ascorbic acid combinations were added, but this effect was not as good as glucose oxidase–hemicellulase. The effects of glucose oxidase and its combinations with ascorbic acid and hemicellulase on dough rheology and bread quality are highly dependent on the amount of enzyme and the original wheat flour quality. PRACTICAL APPLICATIONIn practice, appropriate combinations of glucose oxidase with hemicellulase can be used as improvers in bread making, depending on their combination levels. This study will show the way to new research about glucose oxidase, ascorbic acid and hemicellulose.

Involvement of Na +/K +-ATPase in hydrogen peroxide-induced hypertrophy in cardiac myocytes

We have shown that increased production of reactive oxygen species (ROS) was required for ouabain-induced hypertrophy in cultured cardiac myocytes. In the present study we assessed whether long-term exposure of myocytes to nontoxic ROS stress alone is sufficient to induce hypertrophy. A moderate amount of H 2O 2 was continuously generated in culture media by glucose oxidase. This resulted in a steady increase in intracellular ROS in cultured cardiac myocytes for at least 12 h. Such sustained, but not transient, increase in intracellular ROS at a level comparable to that induced by ouabain was sufficient to stimulate protein synthesis, increase cell size, and change the expression of several hypertrophic marker genes. Like ouabain, glucose oxidase increased intracellular Ca 2+ and activated extracellular signal-regulated kinases 1 and 2 (ERK1/2). These effects of glucose oxidase were additive to ouabain-induced cellular changes. Furthermore, glucose oxidase stimulated endocytosis of the plasma membrane Na +/K +-ATPase, resulting in significant inhibition of sodium pump activity. While inhibition of ERK1/2 abolished glucose oxidase-induced increases in protein synthesis, chelating intracellular Ca 2+ by BAPTA-AM showed no effect. These results, taken together with our prior observations, suggest that ROS may cross talk with Na +/K +-ATPase, leading to the activation of hypertrophic pathways in cardiac myocytes.

Therapeutic effect of llama derived VHH fragments against Streptococcus mutans on the development of dental caries

Streptococcus mutans is the main cause of dental caries. We evaluated the therapeutic effect of variable regions of a llama heavy chain antibody fragments directed against S. mutans named S36-VHH (S for Streptococcus) alone or fused with glucose oxidase (GOx) from Aspergillus niger. Western blot analysis and ELISA revealed binding of the S36-VHH to the streptococcal antigen I/II adhesin molecule of S. mutans serotype C. In a rat-desalivated caries model, daily administration of S36-VHH significantly reduced the development of smooth surface caries. No additional therapeutic effect of GOx was observed. Our results suggest that llama VHH antibodies may be a potential benefit as prophylaxis against dental caries.

Antibacterial Activity of the Glucose Oxidase/Glucose System in Liquid Whole Egg

The effect of glucose oxidase (GOX) in different GOX/glucose combinations on four commonly occurring microorganisms in liquid whole egg was evaluated. The addition of a combination of 500 U GOX and 0.5g glucose in 100 ml liquid whole egg killed Salmonella enteritidis, Micrococcus luteus and Bacillus cereus inoculated at 103cells/ml after 5 days of storage at 7°C, and showed a bacteriostatic activity on Pseudomonas fluorescens. The latter possesses the strongest catalase activity of the four bacteria tested, enabling it to more rapidly break down the hydrogen peroxide produced enzymatically by the GOX/glucose system. The efficacy of the above-mentioned combination was tested on the natural contamination flora of liquid egg and compared to the effect of a simple β-d-glucono-δ-lactone (GDL) treatment (0.7 g/100 ml). The GOX/glucose combination prolonged the lag phase by 6 days. Subsequently, the bacterial flora started to develop, but growth remained retarded by 2 log units. Since GDL did not exert antibacterial activity, growth inhibition by the GOX/glucose system cannot be ascribed to a pH decrease as a result of the production of gluconic acid in the system.

Growth Inhibition by Glucose Oxidase of Selected Organisms Associated With the Microbial Spoilage of Shrimp (Pandalus jordani): In Vitro Model Studies

The effect of glucose oxidase (GOX)-catalase with different GOX-catalase ratios and of the Chemicals produced by GOX, gluconic acid and hydrogen peroxide, were evaluated on four microorganisms usually present in shrimp. Growth inhibition was independent of the enzyme ratio within the limits tested. Hydrogen peroxide inhibited Pseudomonas fluorescens, Hansenula polymorpha and Acinetobacter calcoaceticum. Only Corynebacter aquaticum was inhibited by gluconic acid but was not affected by hydrogen peroxide.

Effects of glucose oxidase in mice

The effects of glucose oxidase, which oxidizes glucose and produces H 2O 2, were studied in mice after intraperitoneal injection of supralethal doses of the enzyme. Such injections cause the appearance of hematin pigment in the plasma, up to 20 per cent of this pigment being methemoglobin. After high lethal doses of glucose oxidase, the hematocrit decreases (readings as low as 7 have been obtained), and the total hematin pigment of whole blood also decreases strikingly. After lower, but stilllethal, doses of the enzyme, the hematocrit increases (readings as high as 80 have been obtained), and the percentage of hematin pigment in whole blood correspondingly increases. At least part of this loss of fluid from the blood is accounted for by increased water content of liver and kidney. After such doses of glucose oxidase, decreases were demonstrated in blood sugar and in liver glycogen.

The Effect of Glucose Oxidase, Penicillin, Sodium Fluoride and Stannous Fluoride on Experimental Rat Caries

The Effect of Glucose Oxidase, Penicillin, Sodium Fluoride and Stannous Fluoride on Experimental Rat Caries