Kinetic Study Of Enzymatic Hydrolysis Research Articles

Enzyme-assisted extraction of fucoidan from Kjellmaniella crassifolia based on kinetic study of enzymatic hydrolysis of algal cellulose

Fucoidan extraction from Kjellmaniella crassifolia was enhanced through β-glucosidase fortified cellulase treatment. Kinetic study of the hydrolysis of isolated seaweed cellulose by commercial enzymes was carried out, and cellulolytic enzyme cocktail was optimized according to the degradation kinetics using response surface methodology for fucoidan extraction. Cellulose (9.88 wt%, d.b.) found in the seaweed was highly crystalline (CrI: 83.24 %). β-glucosidase apparently improved the affinity of the cellulolytic enzymes for the cellulose by eliminating cellobiose feedback inhibition. Treating the seaweed with 30 FPU cellulase supplemented with 286.64 CBU β-glucosidase per gram cellulose, followed by conventional ethanol precipitation, the fucoidan extraction yield based on seaweed feedstock dry matter reached 4.74 %. The total sugar content and sulfate content of the product reached 76.68 % and 22.83 %, respectively, with fucose accounting for 62.46 % of the total sugar. The product extracted under optimal conditions exhibited apparently concentration-dependent antioxidant activity, with IC50 values for DPPH, Hydroxyl and ABTS radical scavenging reaching 2.43 mg/mL, 1.02 mg/mL and 1.12 mg/mL, respectively. The results showed that the proposed enzymatic treatment based on cellulose hydrolysis kinetics effectively disrupted the cell wall and facilitated the release and extraction of fucoidan from the seaweed.

Combining Michaelis-Menten theory and enzyme deactivation reactions for the kinetic study of enzymatic hydrolysis by different pretreated sugarcane bagasse

Conversion of lignocellulose to sugar depends on expensive cellulase and xylanase, hence, improvement of enzyme utilization is important. Enzymatic kinetics can guide researchers toward efficient enzymes utilization. Based on Michaelis-Menten theory and enzyme deactivation reactions, the novel kinetic models describing sugar (glucose and xylose) yield are deduced. The model based on second-order reaction is significantly superior compared to first-order reaction, which is verified by initial and maximum hydrolytic rate. Hydrolytic rate displays a linear relationship with enzyme loading. Sugar yield differs in enzymatic hydrolysis of various pretreated substrates, which is explained by the preferred model. Enzyme deactivation based on the model shows that higher enzyme loading results in reduced activity retention percentage, due to feedback inhibition of products and ineffective adsorption of substrate to enzyme during the hydrolytic process. Therefore, the developed model allows more in-depth study of enzymatic kinetics and provides a useful guide for efficient enzyme utilization.

Kinetic study of enzymatic hydrolysis of starch isolated from sorghum grain cultivars by various methods

Sorghum (Sorghum bicolor (L.) Moench) crops as a source of starch was successfully cultivated in the Algerian Sahara. Starches from white and red sorghum grains were isolated under three steeping conditions for wet-milling process. The isolate starches susceptibility towards glucoamylase hydrolysis to glucose and the kinetic parameters (Km, Vmax, Kcat and Kcat/Km) are studied. The yield of starch isolation ranged from 40.37 to 54.79 %. The starch purity, amylose content, swelling power and water solubility index ranged from 90.00 to 99.08 %, 23.78 to 25.89 %, 10.37 to 12.47 g/g and 10.65 to 18.80 %, respectively. The values of Vmax in g.l−1.min−1 for starch isolated by three methods are 0.20, 0.09 and 0.058 for white grains and 0.10, 0.08 and 0.20 for red grains. The glucose concentration values in g.l−1 after 120 min of hydrolysis at the initial concentration of 20 g.l−1 of starch isolated by three methods are 13, 10.20 and 7.80 for white grains and 10, 13.80 and 11 for red ones. The results of kinetic study show that the hydrolysis of starch by glucoamylase from Aspergillus niger are affected by the source of starch and the conditions of starch isolation from grains.

Effect of popping on sorghum starch digestibility and predicted glycemic index

Effect of popping on carbohydrate, protein, phytic acid and minerals of three varieties (pop sorghum, maldandi and red sorghum) of sorghum were studied. Significant changes (p ≤ 0.05) in the starch degradability including total and soluble amylose content, and resistant starch occurred due to popping; in-vitro protein digestibility along with the content of albumin proteins increased. Starch characteristics had substantial differences among these three varieties which are based on the nature of endosperm and amylose content. Phytic acid content had a reduction of 20%-25% after popping. Glycemic index (GI) determined from kinetic study of enzymatic hydrolysis of sorghum starch was between 85 and 92; the rate constant for hydrolysis for these three varieties were in the range of 0.025 and 0.029min(-1). Popping helped to control phytic acid content in sorghum and enhanced protein as well as starch digestibility.

Effect of the ash on enzymatic hydrolysis of steam-exploded rice straw

The effect of metal ions in ash on enzymatic hydrolysis of crop straw has not attracted sufficient attention. In present study, rice straw with high ash content was taken as an example to study the effect. It was found that the common cations of ash (K(+), Mg(2+), Ca(2+), Al(3+), Mn(2+), Fe(3+), Cu(2+), and Zn(2+)) all showed inhibitive effects on cellulase at different levels, except for the stimulative effects of Ca(2+) and Mg(2+) on beta-glucosidase. Interestingly, washing treatment, combined with steam explosion, could effectively remove the ash cations of rice straw. The kinetic study of enzymatic hydrolysis indicated that, compared with the unwashed steam-exploded rice straw (SERS), the maximal hydrolysis velocity of washed SERS was increased by 12.5%. Therefore, the removal of ash by washing could facilitate the enzymatic hydrolysis of SERS.

Kinetic study of enzymatic hydrolysis of potato starch

This article describes the kinetic study of potato starch enzymatic hydrolysis using soluble enzymes (Novo Nordisk). Different assays divided into four groups were used: reaction time (with which it was possible to reduce the 48-72 hour duration reported in the literature to 16 hours with comparable productivity levels); selecting the set of enzymes to be used (different types were evaluated -BAN and Termamyl as alfa-amylases during dextrinization stage, and AMG, Promozyme and Fungamyl for sacarification reaction- identifying those presenting the best performance during hydrolysis). Reaction conditions were optimized for the process's two stages (dextrinization and sacarification). Enzyme dose, calcium cofactor concentration, pH, temperature and agitation speed were studied for the first stage. Enzyme ratio, pH and agitation speed were studied for sacarification; the latter parameter reported values having no antecedents in the literature (60 rpm and 30 rpm for first and second reactions, respectively). Michaelis Menten kinetics were calculated once conditions had been optimized, varying substrate from 10%-50% P/V, obtaining km and Vmax kinetic parameters for each reaction. A kinetic model was found according to local working conditions which was able to explain potato starch conversion to glucose syrup, achieving 96 dextrose equivalents by the end of the reaction, being well within the maximum range reported in the literature (94-98). Laboratory equipment was constructed prior to carrying out assays which was able to reproduce and improve the conditions reported in the literature, making it a useful, reliable tool for use in assays returning good results.

Improvement on enzymatic hydrolysis of resveratrol glucosides in wine

An enzymatic hydrolysis method, useful for the analysis of total wine resveratrol, was optimised. The wine resveratrol O-glycosides were totally hydrolysed in ∼9 h after incubation with β-glucosidase at 50 °C; then the trans- and cis-aglycones were measured by high-performance liquid chromatography after solid phase extraction (SPE). Kinetic study of enzymatic hydrolysis at different temperatures showed that hydrolysis times were reduced with increasing temperature, up to 50 °C, because the enzyme retains its activity even at this temperature.

Enzymatic degradation of poly[( R)-3-hydroxybutyrate]: secretion and properties of PHB depolymerase from Pseudomonas stutzeri

The secretion mechanism and properties of an extracellular polyhydroxybutyrate (PHB) depolymerase of Pseudomonas stutzeri YM1006, which had been isolated from sea water, were studied in the culture containing poly [( R)-3-hydroxybutyrate] [P(3HB)], ( R)-3-hydroxybutyrate [( R)-3HB] or (S)-3-hydroxybutyrate [( S)-3HB] as sole carbon source. P. stutzeri YM1006 was able to grow on P(3HB), ( R)-3HB and ( S)-3HB. The bacterium secreted a PHB depolymerase into the culture supernatant during growth on P (3HB) and ( R)-3HB, while it did not secrete the enzyme on ( S)-3HB. The PHB depolymerase was purified to electrophoretic homogeneity from the culture medium of P. stutzeri by hydrophobic interaction chromatography and its molecular weight was determined as 60 kDa by electrophoresis on polyacrylamide gel in the presence of sodium dodecyl sulfate. The enzyme was stable at temperatures up to 50 °C in aqueous solution at pH values of 6 to 12. The optimum activity of degrading P (3HB) by the enzyme was observed at pH 7.0. A kinetic study of enzymatic hydrolysis of P(3HB) film was carried out at temperatures from 30 to 45 °C at pH 7.4 in 0.1 M potassium phosphate buffer. The enzymatic degradation product contained monomer and dimer of 3-hydroxybutyric acid, and the monomer was a major product over the whole range of enzyme concentration.