Studies of penicillin g acylase immobilization using highly porous cellulose-based polymeric membrane.

The different ionic molecules/compounds were used as a ligand for the immobilization of penicillin G acylase on the highly porous cellulose-based polymeric membrane having buffer flux 1,746 LMH (L m(-2) h(-1)) at 0.5 bar pressure. The immobilized enzyme activity around 250 U(App) was obtained with the ligand such as proline, tryptophan, casein acid hydrolysate, and brilliant green. Comparatively, proline showed less IMY% (percentage immobilization yield--58) but higher RTA% (percentage of activity retention--71) and specific activity (145 U(App) g(-1)). However, the crosslinked preparation of brilliant green obtained using glutaraldehyde showed 82 +/- 2.7% immobilized enzyme activity after the completion of successive five cycles. In comparison with the free enzyme, the enzyme immobilized on the brilliant green coupled membrane showed around 2.4-fold increase in K (m) value (47.4 mM) as well as similar optimum pH (7.2) and temperature (40 degrees C). The immobilized enzyme retained almost 50% activity after 107 days and 50 cycles of operation. Almost 50% decrease in buffer flux after enzyme immobilization was observed. At the end of the 30 cycles, flux pattern shows around 38% decrease in buffer flux however, after 16 cycles of operation flux moves closer towards the steady state.

Single-Step purification and immobilization of penicillin acylase using hydrophobic ligands.

Five different hydrophobic ligands immobilized on 4% (4XL) and 6% (6XL) crosslinked agarose were used to study the single-step purification of penicillin acylase from cell lysate. The 4XL gels showed relatively higher specific activity and recovery than the 6XL gels. In single-step purification, highly active enzyme (42 U/mg) was obtained using moderately hydrophobic ligand (octyl). The crude enzyme immobilized on octyl gel by adsorption showed significant operational stability over a period of 30 d at room temperature. Reactor studies demonstrated the feasibility of hydrophobic ligands as a medium for immobilization.

Optimization of single-step purification of alkaline protease using different hydrophobic ligands.

The adsorption and desorption pattern of alkaline protease was studied using different aliphatic and aromatic hydrophobic ligands. Overall, higher adsorption was obtained on ligands coupled to 6% cross-linked gel than the 4% gel. The highest adsorption was obtained on butyl (94%) and phenyl (98.4%) of 6% cross-linked gel. The adsorption was dependent on concentration and nature of the ligand. In a single-step operation, almost 20-fold purification with 40% yield of the enzyme was obtained using all the optimized experimental parameters.