Tailoring a robust and recyclable nanobiocatalyst by immobilization of Pseudomonas fluorescens lipase on carbon nanofiber and its application in synthesis of enantiopure carboetomidate analogue

Pseudomonas fluorescens lipase (PFL) was covalently immobilized on carbon nanofiber (CNF) using 1‑ethyl‑3‑[3‑dimethylaminopropyl] carbodiimide (EDC)/N‑hydroxysuccinimide (NHS). Surface functionalization of carbon nanofiber augments dispersibility as well as efficiency of covalent immobilization. Crucial parameters for immobilization such as pH, enzyme-support ratio, reaction time and mixing rate were optimized using one factor at a time (OFAT) approach. The nanobiocatalyst prepared under optimized conditions demonstrated a ten-fold increase in enzyme activity and the advantage of high thermal stability (up to 85 °C) along with 10 cycles of reusability. Subsequently practical application of the nanobiocatalyst was explored in the kinetic resolution of racemic 1‑phenylethanol into (S)‑1‑phenylethanol [C = 49.1%, ee_p = 99.5%, ee_s = 98.5% and E value = 151.4] followed by Mitsunobu reaction with a substituted pyrrole, giving an enantiopure (R)-carboetomidate analogue (yield = 83%).

Development of nanobiocatalysts through the immobilization of Pseudomonas fluorescens lipase for applications in efficient kinetic resolution of racemic compounds

The present work reports covalent immobilization of Pseudomonas fluorescens lipase (PFL) on functionalized multiwalled carbon nanotubes (MWCNTs) as a nanobiocatalyst (NBC). This nanobiocatalyst facilitates efficient kinetic resolution of (RS)-1-phenylethanol into (S)-1-phenylethanol [C=49.7%, ee_p=99.5%, ee_s=98.1% and E value=191.4]. The immobilized preparation (MWCNTs-PFL) showed ten-fold increase in activity, thermal stability upto 80 °C and recyclability (8 cycles). MWCNTs-PFL nanobioconjugate demonstrated better stability and enhanced activity compared to covalently immobilized PFL on other matrices (silver nanoparticles, gold nanoparticles and chitosan beads) used for the study. A statistical design [response surface methodology (RSM)] employed for the optimization of enzyme immobilization parameters made this study statistically more significant. Overall, the newly developed nanobiocatalyst has applications towards the kinetic resolution of racemic compounds.