ABSTRACT
Three different beta-glycosidase sequences of Ttebgl3, Tpebgl1 and Tpengl3 from Thermotoga thermarum DSM 5069 and Thermotoga petrophila RKU-1 were analyzed. Also, the influence of temperature, pH, concentration of DMSO, metal ions and kinetic constant on catalytic conversion of baicalin had been compared. The results indicated that the optimal pH and optimum temperature for transformation of baicalin was 4.5 85 °C, 5.0 80 °C and 5.5 80 °C, respectively. The family GH3 beta-glycosidase Ttebgl3 and Tpebgl3 had the better DMSO tolerance. The activation effect of the metal ions on the catalytic conversion of baicalin was not obvious, and the inhibition of the GH3 family beta glucosidase was significantly stronger than that of the GH1 family. The kinetic constants of three different beta-glucosidases catalyzed baicalin were significantly different. The Km and Vmax values of Tpebgl1, Tpebgl3 and Ttebgl3 were 0.029 2 mmol·L⁻¹ 4.85 U·mg⁻¹, 0.268 6 mmol·L⁻¹ 121.04 U·mg⁻¹ and 0.391 8 mmol·L⁻¹ 308.90 U·mg⁻¹, respectively. Family GH3 beta-glycosidase converted more baicalin than family GH1 with the optimal conditions, 0.02 g baicalin, and the conversion rate was 68%, 97.3%, 97.31% respectively. The results of the study provided a guarantee for the transformation of baicalin.
ABSTRACT
The reaction conditions of baicalin hydrolyzed into baicalein by a kind of thermophilic and sugar-tolerant beta-glucosidase were studied in this paper. The beta-glucosidase could catalyze baicalin into baicalein well in the acetic acid-sodium acetate buffer. The optimal enzyme activity was at 85 degrees C and pH 5.5. The enzyme was stable at the temperature less than 85 degrees C and pH range of 5-7.5. The maximum reaction rate V. and michaelis constant K. were 0.41 mmol x L(-1) x min(-1) and 3.31 mmol x L(-1) respectively. Different metal ions had different effects on the activity of enzyme. Na+ existing in acetic acid-sodium acetate buffer had an activation effect on enzyme. The enzyme activity was enhanced by the concentrations of glucose below 0.6 mol x L(-1), and was gradually inhibited when monosaccharide concentration was over 0.6 mol x L(-1). When the monosaccharide concentration reached 1.2 mol x L(-1), the inhibition rate of enzyme activity was about 50%, which showed good glucose tolerance. The good reaction conditions through the experiment have been determined as follows, the substrate: enzyme dose was 1 g: 0.2 mL, acetic acid-sodium acetate buffer pH 5.5, reaction temperature 85 degrees C, reaction time 10 h, and the enzymatic hydrolyzation ratio could reach 97%.
Subject(s)
Biocatalysis , Enzyme Stability , Flavanones , Chemistry , Flavonoids , Chemistry , Glucose , Chemistry , Hot Temperature , Hydrolysis , Kinetics , beta-Glucosidase , ChemistryABSTRACT
<p><b>OBJECTIVE</b>To study the relationship between CT imaging classification criteria and the prognosis of severe acute pancreatitis (SAP).</p><p><b>METHODS</b>From January 2000 to December 2009, 62 cases with SAP were analyzed, retrospectively. They were all executed CT examination in 72 h after admission, and their CT imaging were classified as grade C (n = 13), grade D (n = 26), and grade E (n = 23) according to the Balthazar classification criteria and also classified as grade I (n = 11), grade II (n = 39), grade III (n = 12) according to the Balthazar CT severity index (CTSI) criteria, respectively. The values of these two different classification criteria in assessing the prognosis of SAP were studied, such as length of hospital stay, fever days, fasting days, white blood cell recovery days, serum amylase recovery days, pancreatic pseudocyst, organ failure, need for transit operations, and death. By studying the receiver operating characteristic (ROC) curves, which were drawn by the area under cures, the values of the two different classification criteria were compared in assessing the prognosis of SAP.</p><p><b>RESULTS</b>The Balthazar classification criteria was valuable in assessing white blood cell recovery days (F = 4.035, P = 0.023) and pseudocyst (χ(2) = 8.066, P = 0.018). No statistical differences were found, however, between other clinicopathological parameters and the prognosis of SAP, according to the Balthazar classification criteria. The patients with low-grade of CTSI classification criteria enjoyed better prognosis, and patients in grade I or II got lower incidence of organ failure, need for transit operations and pseudocyst than that in grade III. The results above suggested that CTSI classification criteria, comparing with Balthazar CT classification criteria, was more valuable in predicting the incidence of organ failure, pseudocyst, need for transit operation, and mortality in SAP (P < 0.01).</p><p><b>CONCLUSION</b>The CTSI classification criteria has a great value in assessing the prognosis of SAP.</p>