Action pattern of alpha‐amylase from Aspergillus oryzae in concentrated media

International audienceThe influence of concentrated maltotetraose solutions on fungal alpha‐amylase activity and specificity has been determined. It has been found that the enzyme is not inhibited by 500 g/L substrate concentration and that transglycosylation reactions are increased with rising substrate concentration. The amount of oligosaccharides of polymerization degree higher than maltotetraose reaches 20% (w/w). Moreover, the effect of polyhydric alcohols, known as water activity depressors has been analyzed: the presence of polyols does not modify the amount of transglycosylation products, but changes the hydrolysis pattern by favoring the formation of low polymerization degree oligosaccharides

Action pattern of alpha‐amylase from Aspergillus oryzae in concentrated media

International audienceThe influence of concentrated maltotetraose solutions on fungal alpha‐amylase activity and specificity has been determined. It has been found that the enzyme is not inhibited by 500 g/L substrate concentration and that transglycosylation reactions are increased with rising substrate concentration. The amount of oligosaccharides of polymerization degree higher than maltotetraose reaches 20% (w/w). Moreover, the effect of polyhydric alcohols, known as water activity depressors has been analyzed: the presence of polyols does not modify the amount of transglycosylation products, but changes the hydrolysis pattern by favoring the formation of low polymerization degree oligosaccharides

Effect of polyols on fungal alpha-amylase thermostability

International audienceThe influence of different polyols (ethylene glycol, glycerol, erythritol, xylitol, and sorbitol) on the thermostability of fungal alpha-amylase at 60°C has been studied. The results obtained show a stabilizing effect in the presence of polyols. In the case of 4 m sorbitol solution, the enzyme half-life is 2000-fold longer than in pure water. These polyols have been found as competitive inhibitors for alpha-amylase andtheir stabilizing effect has been correlated to their affinity constant except for sorbitol. The influence of two polyol isomers (arabitol and mannitol) on activity and stability of alpha-amylase has also been investigated

Étude de l'énantiosélectivité de la lipase B de Candida antarctica à l'aide d'un bioréacteur solide-gaz

LA ROCHELLE-BU (173002101) / SudocSudocFranceF

Preparative anion-exchange chromatography: the alternative of column-overload methods

International audienceThe objective of preparative separation is to purify the largest amount of material in the shortest time and at a minimum cost, i.e. to maximize throughput. One of the techniques for increasing throughput is to overload the column while maintaining purity and cycle time at the same level. This principle is applied in sample displacement mode chromatography, in which the column is overloaded with sample mixture until it is completely saturated. Soybean trypsin inhibitor was purified from a crude protein extract by this technique using an analytical anion-exchange column with small particle size (20,um). The comparison of these results, using the criterion of throughput, with those derived from a conventional scale-up, using a 40-μm preparative column, led to the conclusion that the overloaded 20-μm column gave a higher throughput than the 40-μm column

Amidase activity and thermal stability of human thrombin

International audiencePrevious studies of amidase activity of human α-thrombin have yielded variable results and the decrease of this activity as a function of time and temperature has never been quantified. As this protease is an efficient tool in biochemistry and biotechnology thanks to its extreme selectivity, amidase activity and stability of thrombin were investigated with the synthetic substrate Tos-Gly-Pro-Arg-pNa. Enzyme activity as a function of temperature showed an optimum peak at 45‡C. The pH dependence of the activity showed a maximum around 9.5. The addition of NaCl promoted an increase of the activity. Stability of thrombin decreased rapidly when increasing the temperature from 25-45‡C and when diluting the enyzme. The presence of glycerol and ethylene glycol promoted a small increase of thrombin half life, whereas polyethylene glycol had a more pronounced positive effect even at very low concentrations

Amidase activity and thermal stability of human thrombin

International audiencePrevious studies of amidase activity of human α-thrombin have yielded variable results and the decrease of this activity as a function of time and temperature has never been quantified. As this protease is an efficient tool in biochemistry and biotechnology thanks to its extreme selectivity, amidase activity and stability of thrombin were investigated with the synthetic substrate Tos-Gly-Pro-Arg-pNa. Enzyme activity as a function of temperature showed an optimum peak at 45‡C. The pH dependence of the activity showed a maximum around 9.5. The addition of NaCl promoted an increase of the activity. Stability of thrombin decreased rapidly when increasing the temperature from 25-45‡C and when diluting the enyzme. The presence of glycerol and ethylene glycol promoted a small increase of thrombin half life, whereas polyethylene glycol had a more pronounced positive effect even at very low concentrations