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1630423 
Journal Article 
Purification and Properties of a Lipase from Thermophilic Geobacillus stearothermophilus Strain-5 
Sifour, M; Saeed, HM; Zaghloul, TI; Berekaa, MM; Abdel-Fattah, YR 
2010 
Yes 
International Journal of Biological Chemistry
ISSN: 1819-155X 
4 
4 (Dec 2010) 
203-212 
The study was aimed to purify the extracellular lipase produced from a thermophilic Geobacillus stearothermophilus strain-5. The enzyme was purified using ultrafiltration followed by three column chromatographies: Q-Sepharose ion exchange chromatography, Sephadex G-100 gel filtration and adsorption on hydroxyl apatite to 22.6-fold with 8.8% recovery. The lipase had a molecular weight of about 61 kDa. The enzyme showed optimal activity at 55-60C and pH 8.0 and retained about 87.5% of its original activity after exposure to 70C for 15 min. Furthermore, 95-100% of the original activity was retained after incubation at pH 5-9 at 60C for 30 min. The presence of 1 mM of the following metal ions: Fe super(2+), Ca super(2+), Mn super(2+) and Mg super(2+) enhance the lipase activity whereas Zn super(2+), Hg super(2+) and Cu super(2+) inhibited it. The purified enzyme exhibited good tolerance to some organic solvents especially butanol and isopropanol. The presence of detergent such as SDS, Tween 20, Tween 80 and Triton X-100 had a slight effect on the lipolytic activity. The enzyme hydrolyzes both soluble and insoluble emulsified substrates; it showed highest affinity to tributyrin. The values of K sub(m) and V sub(max) of the lipase using p-nitrophenyl palmitate as calculated from the Linweaver-Burk plot were 0.588 mg mL super(-1) and 129.7 U mL super(-1), respectively. The obtained enzyme showed stability to different pH values, temperatures and tolerance to some detergents and organic solvents. 
Copper; Geobacillus; Metals; Sodium lauryl sulfate; Zinc; Ion exchange; Filtration; Column chromatography; Adsorption; Triacylglycerol lipase; butanol; apatite; Detergents; Temperature tolerance; p-nitrophenyl palmitate; pH effects; Enzymes; Ultrafiltration; Purification; Calcium; Solvents; Magnesium; Iron; Molecular weight