Enzyme activity assay: Esterases

In the following figures enzyme activities of the supernatant of the esterases EstCS2 and LIpB are shown. All results were obtained from biological triplicates. The detailed method for the activity determination is shown here: LINK At the N-terminal end of the esterase EstCS2 a signal peptide (PelB) is added. Therefore the gene induction leads to enzyme expression and the expression of the signalpeptide and the secretion of the enzyme is enabled. The enzyme activity of EstCS2 raises with the induction level for gene expression and with the substrate concentration. A maximum of 246,5 U is gained with 20 mM p-Nitrophenyl butyrate and 1 mM arabinose. The enzyme activities between the induction levels of 2 mM arabinose and 3 mM arabinose isn’t different. The enzyme activity is highest with an induction level of 1 mM arabinose instead of an induction level of 2 or 3 mM arabinose. This could be explained with less movement flexibility of the esterases if high gene expression rates are induced. We would further recommend to induce the gene expression with less arabinose concentrations and investigate the enzyme activity with 0.1 mM, 0.5 mM and 1 mM arabinose.

Figure 3:Illustration of the esterase activity [U] of EstCS2 in the supernatant dependend on time and substrate concentration (2.5, 5, 10, 15, 20 mM). The standard abbreviation was calculated from biological triplicates.