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A thermostable metalloprotease, produced from an environmental strain of Candida kefyr 41 PSB, was purified 16 fold with a 60% yield by cold ethanol precipitation and affinity chromatography (bentonite-acrylamide-cysteine microcomposite). The purified enzyme appeared as a single protein band at 43 kDa. Its optimum pH and temperature points were found to be 7.0 and 105 °C, respectively. K m and V max values of the enzyme were determined to be 3.5 mg/mL and 4.4 μmol mL −1 min −1 , 1.65 mg/mL and 6.1 μmol mL −1 min −1 , using casein and gelatine as the substrates, respectively. The activity was inhibited by using ethylenediamine tetraacetic acid (EDTA), indicating that the enzyme was a metalloprotease. Stability of the enzyme was investigated by using thermodynamic and kinetic parameters. The thermal inactivation profile of the enzyme conformed to the first order kinetics. The half life of the enzyme at 95, 105, 115, 125 and 135 °C was 1310, 610, 220, 150, and 86 min, respectively. [ABSTRACT FROM AUTHOR]

An organic solvent tolerant lipase gene from Staphylococcus epidermidis AT2 was successfully cloned and expressed with pTrcHis2 in E. coli TOP10. Sequence analysis revealed an open reading frame (ORF) of 1,933 bp in length which coded for a polypeptide of 643 amino acid residues. The polypeptide comprised of a signal peptide (37 amino acids), pro-peptide and a mature protein of 390 amino acids. Expression of AT2 lipase resulted in an 18-fold increase in activity, upon the induction of 0.6 mM IPTG after a 10 h incubation period. Interestingly, this lipase was stable in various organic solvents (25% (v/v), mainly toluene, octanol, p-xylene and n-hexane). Literature shows that most of the organic solvent stable bacterial lipases were produced by Pseudomonas sp. and Bacillus sp., but very few from Staphylococcus sp. This lipase demonstrates great potential to be employed in various industrial applications.

The NaCl-activated and detergent-stable proteinases from Virgibacillus halodenitrificans SK1-3-7 isolated from fish sauce fermentation were purified and characterized. The enzymes with molecular masses of 20 and 36 kDa showed caseinolytic activity on a zymogram. Optimum azocaseinolytic activity was at 60 °C and pH 9. The proteolytic activity increased in the presence of 10 mM CaCl and 0.5 M NaCl and showed high stability at 0-2 M NaCl. The enzymes were stable at pH 4-10 and 10-50 °C. The enzymes preferably hydrolyzed Suc-Ala-Ala-Pro-Phe-pNA and were completely inhibited by phenylmethanesulfonyl fluoride (PMSF), showing subtilisin-like characteristics. Activity and stability remained high in the presence of HO and various surfactants. The enzymes exhibited high stability (>95 %) in various organic solvents (DMSO, butanol, ethanol, 2-propanol, and acetonitrile) at concentration of 50 %. The V. halodenitrificans SK1-3-7 proteinases showed potential as a biocatalyst in aqueous-organic solvent systems and as an additive in laundry detergent. [ABSTRACT FROM AUTHOR]

The gene encoding a cold-adapted, organic solvent stable lipase from a local soil-isolate, mesophilic Staphylococcus epidermidis AT2 was expressed in a prokaryotic system. A two-step purification of AT2 lipase was achieved using butyl sepharose and DEAE sepharose column chromatography. The final recovery and purification fold were 47.09 % and 3.45, respectively. The molecular mass of the purified lipase was estimated to be 43 kDa. AT2 lipase was found to be optimally active at pH 8 and stable at pH 6-9. Interestingly, this enzyme demonstrated remarkable stability at cold temperature (<30 °C) and exhibited optimal activity at a temperature of 25 °C. A significant enhancement of the lipolytic activity was observed in the presence of Ca, Tween 60 and Tween 80. Phenylmethylsulfonylfluoride, a well known serine inhibitor did not cause complete inhibition of the enzymatic activity. AT2 lipase exhibited excellent preferences towards long chain triglycerides and natural oils. The lipolytic activity was stimulated by dimethylsulfoxide and diethyl ether, while more than 50 % of its activity was retained in methanol, ethanol, acetone, toluene, and n-hexane. Taken together, AT2 lipase revealed highly attractive biochemical properties especially because of its stability at low temperature and in organic solvents. [ABSTRACT FROM AUTHOR]

An organic solvent tolerant lipase gene from Staphylococcus epidermidis AT2 was successfully cloned and expressed with pTrcHis2 in E. coli TOP10. Sequence analysis revealed an open reading frame (ORF) of 1,933 bp in length which coded for a polypeptide of 643 amino acid residues. The polypeptide comprised of a signal peptide (37 amino acids), pro-peptide and a mature protein of 390 amino acids. Expression of AT2 lipase resulted in an 18-fold increase in activity, upon the induction of 0.6 mM IPTG after a 10 h incubation period. Interestingly, this lipase was stable in various organic solvents (25% (v/v), mainly toluene, octanol, p-xylene and n-hexane). Literature shows that most of the organic solvent stable bacterial lipases were produced by Pseudomonas sp. and Bacillus sp., but very few from Staphylococcus sp. This lipase demonstrates great potential to be employed in various industrial applications. [ABSTRACT FROM AUTHOR]