Elution fractions containing His6-tagged LipBL and variants were diluted 50-fold and concentrated using centrifugal filter units with 10 kDa size-exclusion membranes (Centricon,Millipore) to reduce the concentration of imidazole, which interferes with activity assays. Protein concentrations were determined after purification using Advanced Image Data Analysis (AIDA) 2D software (version 4.18.028) with a calibration curve based on BSA