Protein Engineering

Biography

Biography: Irfana Mariam

Abstract

Aspergillus niger strain IIB-247 was used for production of Glucose oxidase using medium containing glucose 6%, peptone 0.3%, (NH4)2HPO4 0.04%, KH2PO4 0.0188%, MgSO4.7H2O 0.0156%, CaCO3 3.5%. Maximum production (12.12 ± 0.01 U/mg) was obtained at pH 7 and temperature and 30°C respectively after 72 hours of fermentation. Optimum glucose oxidase production coincided with glucose depletion (87.5%). Ammonium sulfate precipitation and Ion exchange chromatography resulted in 53.5 % yield and 16. 81 fold purification with enhancement of specific activity (203.56 ± 0.02 U/mg). Kinetic characterization of enzyme revealed D-Glucose as highly specific substrate for enzyme with Km value of 30.5 mM. Thermodynamic evaluation of enzyme revealed activation energy (Ea) as 13.14 KJ/mol, enthalpy of activation (ΔH) as 10.87KJ/mol and entropy of activation (ΔS) as -1.139 KJ/mol respectively. The enzymes catalytic activity was observed to be reduced by some heavy metals such as i.e. Hg2+, Pb2+, Cu+ and Cd2+. The enzyme remained stable at pH 6. Maximum shelf life of the enzyme was observed in lyophilized form at -20°C for a period of 2 months. All of the above mentioned characters of GOX made it a potential candidate in food industry for residual glucose and oxygen removal in foods and beverages in order to prolong their shelf lifes. Glucose oxidase can also be used to remove oxygen from the top of bottled beverages before they are sealed. In addition, glucose oxidase is used to prevent colour and flavour loss from foods and beverages. Apart from that it can be used for estimation of blood glucose level as well.