Current Issue : July-September Volume : 2017 Issue Number : 3 Articles : 2 Articles
Pectinases are the enzymes that break down pectin, a polysaccharide substrate that is found in the cell walls of plants. One of the most studied and widely used commercial pectinases is polygalacturonase. It is useful because pectin is the jelly-like matrixes which helps cement plant cells together and in which other cell wall components, such as cellulose fibrils, are embedded. Therefore pectinase enzymes are commonly used in processes involving the degradation of plant materials, such as speeding up the extraction of fruit juice from fruit. Considering the wide applications of pectic enzymes in various industries, the current research is intended to concentrate in the world of pectic enzymes with following objectives-Isolation of microorganisms which produce pectinase from natural sources i.e., from spoiled fruits /vegetables, purify the enzyme in three steps and optimise the various process parameters. The present study deals with the production of pectinase enzyme by a strain of Aspergillus niger, isolated from rotten tomato. The enzyme was quantified and purification was performed by ammonium sulphate precipitation, dialysis and column chromatography. Optimisation studies were carried out to identify the suitable conditions for maximum production of pectinase enzyme....
Mucor circinelloides F6-3-12 tannase was conjugated to several activated polysaccharides and polyethylene glycol (PEG). The enzyme conjugates were evaluated for the kinetic and thermodynamic stability. The conjugated enzyme with PEG had the highest thermal stability (T1/2 at 50°C = 704.54 min). Compared to the native tannase, the PEG-conjugated preparation exhibited lower activation energy (Ea ), lower deactivation constant rate (kd), higher t1/2 and D values (decimal reduction time) within the temperature range of 40–60°C. The values thermodynamic parameters entropy (ΔS*) and enthalpy (ΔH*) for irreversible thermal inactivation of the enzyme was significantly decreased upon conjugation with PEG. Further, the calculated value of deactivation energy for irreversible thermal inactivation (Ead) for PEG-conjugated tannase was 102 KJ mole-1 higher over the native one. The results of thermodynamic analysis for tannic acid hydrolysis indicated that the enthalpy of activation (ΔH*) and free energy of activation (free energy of substrate binding) ΔG*E–S and (ΔG*), (free energy of transition state) ΔG*E–T values were lower for the conjugated tannase. Similarly, there was significant improvement of kcat, kcat/Km values. Further, the calculated value of activation energy for thermal denaturation (Ead) for PEG- conjugated tannase was 102 KJ mole-1 higher over the native one. The results of thermodynamic analysis for tannic acid hydrolysis indicated that the enthalpy of activation (ΔH*) and free energy of activation (free energy of substrate binding) ΔG*E–S and (ΔG*), (free energy of transition state) ΔG*E–T values were lower for the conjugated tannase. Similarly, there was significant improvement of kcat, kcat/Km values....
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