The esterolytic activity of a sample is routinely estimated by employing the pNpp assay (20). The basis of this assay procedure is the colorimetric estimation of pNp released as a result of enzymatic hydrolysis of pNpp at 405 nm. The substrate solution was prepared by adding solution
A (30 mg pNpp in 10 mL isopropanol) to solution Lorlatinib ic50 B (0.1 g gum arabic and 0.4 mL Triton X-100 in 90 mL of 50 mM Tris- HCl buffer, pH 8.0) with stirring. The mixture of 180 μL substrate solution and 20 μL enzyme solution was incubated at 37°C for 15 min. Absorbance was measured at 405 nm (A405) originating from p-nitrophenol, which was generated by the action of lipase. The substrate specificity of the purified enzyme was analyzed
using the following substrates of pNp-fatty acyl esters: decanoate (C10), palmitate (C16) and stearate (C18). The reactions were carried out as described above. The lipase activity of the sample was determined by incubation with tributyrin. The method described by Lotrakul and Dharmsthiti was used to examine activity (21). Briefly, 40 μL tributyrin was sonicated in 1.0 mL of 0.1 FK228 M Tris-HCl (pH 8.0) containing 1 mM calcium chloride for 3 min. After sonication, the solution was divided into four tubes (250 μL/tube). A different amount of purified protein (250 μL) was added to each tube and the reaction mixture incubated at 37°C for 6 hrs. After incubation, the reaction products were extracted by the addition of 0.5mL diethyl ether. The extract was concentrated by evaporation and applied to a silica gel plate (TLC Silica Gel 60; Merck KGaA, Darmstadt, Germany). Plates were developed with a 96:4:1 mixture (by volume) of chloroform:acetone:acetic acid. The spots of glycerides were visualized by exposure to 50% sulfuric acid vapor and then heating at 160°C for 30 min. The assay to test the thermostability of purified lipase was performed by heating the enzyme solution at 30°C, 40°C, 50°C,
60°C, 70°C, Anacetrapib 80°C, and 100°C for 10 min. The remaining activity after heating was assayed as described above using pNp-palmitate as a substrate. To determine the nucleotide sequence of the target protein of A. sorbria 288, two sets of oligonucleotides were designed with reference to the nucleotide sequence of extracellular lipase of A. hydrophila ATCC7966. The extracellular lipase of A. hydrophila ATCC7966 is composed of 805 amino acid residues (2415 nucleotides). The first set of oligonucleotides was composed of oligomer-1 (5′-TCTGCACGTCAAACTCTTCG-3′, forward) and oligomer-2 (5′-TCGAACTTGAACAGGGCATC-3′, reverse). The DNA fragment amplified by the first set of oligonucleotides covers the region from − 467 to 1784 of the extracellular lipase gene (+ 1 nucleotide is A of the initiation codon of translation). The second set was composed of oligomer-3 (5′-GGCAAGCCGCTGGATGCCGA-3′, forward) and oligomer-4 (5′-CGCTGTTTGGCGGCCTCTCC-3′, reverse).