Saturday, November 3, 2007

Thermostable glucose isomerase from psychrotolerant Streptomyces species

Bidur Dhungel1, Manoj Subedi1, Kiran Babu Tiwari1,2, Upendra Thapa Shrestha2, Subarna Pokhrel3 and Vishwanath Prasad Agrawal1, 2
1Universal science College, Pokhara University, Kathmandu, Nepal
2Research Laboratory for Agricultural Biotechnology and Biochemistry, Kathmandu, Nepal
3Department of Enzyme Engineering, Seoul National University, Korea
Corresponding Address: Dr. Vishwanath P. Agrawal, Professor of Biochemistry, Universal Science College, Pokhara University, Kathmandu. Email: vpa@wlink.com.np

Accepted in Journal of Nepal Biotechnology Association

ABSTRACT
Glucose isomerase (EC 5.3.1.5) was extracted from Streptomyces spp., isolated from Mt. Everest soil sample, and purified by ammonium sulfate fractionation and Sepharose-4B chromatography. A 7.1 fold increase in specific activity of the purified enzyme over crude was observed. Using glucose as substrate, the Michaelis constant (KM) and maximal velocity (Vmax) were found to be 0.45M and 0.18U/mg. respectively. The optimum substrate (glucose) concentration, optimum enzyme concentration, optimum pH, optimum temperature, and optimum reaction time were 0.6M, 62.14μg/100μl, 6.9, 70ºC, and 30 minutes, respectively. Optimum concentrations of Mg2+ and Co2+ were 10mM and 1mM, respectively. The enzyme was thermostable with half life 30 minutes at 100ºC.

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