High level expression and characterization of a novel thermostable, organic solvent tolerant, 1,3-regioselective lipase from Geobacillus sp. strain ARM.
ABSTRACT The mature ARM lipase gene was cloned into the pTrcHis expression vector and over-expressed in Escherichia coli TOP10 host. The optimum lipase expression was obtained after 18 h post induction incubation with 1.0mM IPTG, where the lipase activity was approximately 1623-fold higher than wild type. A rapid, high efficient, one-step purification of the His-tagged recombinant lipase was achieved using immobilized metal affinity chromatography with 63.2% recovery and purification factor of 14.6. The purified lipase was characterized as a high active (7092 U mg(-1)), serine-hydrolase, thermostable, organic solvent tolerant, 1,3-specific lipase with a molecular weight of about 44 kDa. The enzyme was a monomer with disulfide bond(s) in its structure, but was not a metalloenzyme. ARM lipase was active in a broad range of temperature and pH with optimum lipolytic activity at pH 8.0 and 65°C. The enzyme retained 50% residual activity at pH 6.0-7.0, 50°C for more than 150 min.
Conference Proceeding: Chemical/biological contaminant detector for aqueous environments: preliminary report[show abstract] [hide abstract]
ABSTRACT: Paired surface transverse wave resonators operating near 500 MHz are being used as the sensing element in a chemical/biological detector capable of operating in water. Initially, the design of the surface transverse wave detector is discussed. Then, the major problems uncovered with the prototype detector are reviewed with an emphasis on solutions to these problems that will be implemented in a second-generation “smart” detectorFrequency Control Symposium, 1994. 48th., Proceedings of the 1994 IEEE International; 07/1994