Investigating the Impact of Various Parameters On the Activity of Acid Phosphatases from Seedlings of Coronopus didymus

The thermal stability of purified acid phosphatase from the germinating seedlings of Coronopus didymus (Jangli halon) was investigated by studying the impact of various thermodynamic parameters [t_1/2, E_d, ΔH° (enthalpy change), ΔG° (free energy change), and ΔS° (entropy change)] of heat treatment in the temperature range of 55-75 °C. The thermal denaturation of acid phosphatase, assessed by loss in activity, was evidently followed by first-order kinetics, which varies with time and yield during the process of denaturation. The half-life of the enzyme was 693 min at 55 °C. The E_d (activation energy of denaturation) was calculated by the Arrhenius plot (30 kcal mol^-1), and the Z-value was 17.3 °C. The various thermodynamic parameters studied were as follows: ΔH°, the change in enthalpy of inactivation, was 121.93 kJ mol^-1 at 55 °C; ΔG°, the change in free energy of inactivation, was 110.65 kJ mol^-1 at 55 °C; and ΔS°, the change in entropy of inactivation, was 34.39 J mol^-1 k^-1 at 55 °C. This suggests that acid phosphatase activity is thermostable to long heat treatment up to 60 °C.

Production of glucose and fructose syrups from cassava (Manihot esculenta Crantz) starch using enzymes produced by microorganisms isolated from Brazilian Cerrado soil

The high demands for sugars and the development of enzymatic technology have increased the production of sweeteners, especially for glucose and fructose syrups. This work describe a technology for glucose and fructose syrups from Brazilian cassava starch using enzymes produced by soil microrganisms isolated from the Brazilian Cerrado soil. Firstly, Aspergillus niger and Streptomyces sp. were isolated from the soil and used as glucoamylase (GA) and glucose isomerase (GI) producer sources. After characterization, GA and GI exhibited optimum pH 4.5 and 8.0, respectively. GA showed maximum activity at 60 ºC and GI at 85 ºC. GA and GI retained 65 and 80%, respectively, of initial activity after 180 minutes of incubation at 60 ºC. The kinetic parameters Km and Vmáx were 0.476 (mg.mL-1) and 8.58 (µmol/minute) for GA and 0.082 (M) and 48.20 (µmol/minute) for GI. The maximum glucose syrups production occurred after 24 hours of reaction with a 98% yield. The production of fructose syrups with 42% (w/v) was reached after 96 hours of reaction.