Effects of macroporous resin size on Candida antarctica lipase B adsorption, fraction of active molecules, and catalytic activity for polyester synthesis.
Methyl methacrylate resins with identical average pore diameter (250 A) and surface area (500 m2/g) but with varied particle size (35 to 560-710 microm) were employed to study how immobilization resin particle size influences Candida antarctica Lipase B (CALB) loading, fraction of active sites, and catalytic properties for polyester synthesis. CALB adsorbed more rapidly on smaller beads. Saturation occurred in less than 30 s and 48 h for beads with diameters 35 and 560-710 microm, respectively. Linearization of adsorption isotherm data by the Scatchard analysis showed for the 35 microm resin that: (i) CALB loading at saturation was well below that required to form a monolayer and fully cover the support surface and (ii) CALB has a high affinity for this resin surface. Infrared microspectroscopy showed that CALB forms protein loading fronts for resins with particle sizes 560-710 and 120 microm. In contrast, CALB appears evenly distributed throughout 35 microm resins. By titration with p-nitrophenyl n-hexyl phosphate (MNPHP), the fraction of active CALB molecules adsorbed onto resins was <50% which was not influenced by particle size. The fraction of active CALB molecules on the 35 microm support increased from 30 to 43% as enzyme loading was increased from 0.9 to 5.7% (w/w) leading to increased activity for epsilon-caprolactone (epsilon-CL) ring-opening polymerization. At about 5% w/w CALB loading, by decreasing the immobilization support diameter from 560-710 to 120, 75, and 35 microm, conversion of epsilon-CL % to polyester increased (20 to 36, 42, and 61%, respectively, at 80 min). Similar trends were observed for condensation polymerizations between 1,8-octanediol and adipic acid.
Chen
Bo
B
NSF Industry/University Cooperative Research Center for Biocatalysis and Bioprocessing of Macromolecules, Polytechnic University, 6 Metrotech Center, Brooklyn, NY 11201, USA.
Miller
Elizabeth M
EM
Miller
Lisa
L
Maikner
John J
JJ
Gross
Richard A
RA
D000327:Adsorption; D001665:Binding Sites; D002384:Catalysis; D004800:Enzymes, Immobilized / Q000378:metabolism*; D005656:Fungal Proteins; D008049:Lipase / Q000378:metabolism*; D010316:Particle Size; D011091:Polyesters / Q000138:chemical synthesis*; D016062:Porosity; D012117:Resins, Synthetic; D013055:Spectrophotometry, Infrared
D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D011091:Polyesters; D012117:Resins, Synthetic; D008049:Lipase; C431349:lipase B, Candida antarctica