The functionalized membrane was transferred into round bottom glass flasks containing 5 mL of buffered solution (MES or HEPES 0.1 M buffer, PLP 1 mM, sodium pyruvate 10 mM) for enzyme immobilization. The latter contained the desired TA concentration (C0) and was set either at pH 8 with the HEPES buffer or at pH 5.5 with the MES buffer. Incubation was done for 18 hours at 35 °C under gentle stirring. The resulting membrane-immobilized transaminase was either directly rinsed or post-treated and then rinsed. Post-treatment was done with glutaraldehyde (GA, 1 wt.%) or sodium alginate (SA, 0.2 wt.%) aqueous solutions for 1 hour (unless stated otherwise) at 25 °C in an attempt to prevent TA leaching . Rinsing was done by suspending the membrane in 5 mL of rinsing solution (containing HEPES 0.1 M buffer, PLP 1 mM, sodium pyruvate 10 mM) for 30 minutes (repeated two times), to eliminate the loosely attached enzymes.