Effects of porous polystyrene resin parameters on Candida antarctica lipase B adsorption, distribution, and polyester synthesis activity.
Polystyrene resins with varied particle sizes (35 to 350-600 microm) and pore diameters (300-1000 A) were employed to study the effects of immobilization resin particle size and pore diameter on Candida antarctica Lipase B (CALB) loading, distribution within resins, fraction of active sites, and catalytic properties for polyester synthesis. CALB adsorbed rapidly (saturation time </= 4 min) for particle sizes </= 120 microm (pore size = 300 A). Infrared microspectroscopy showed that CALB forms protein loading fronts regardless of resin particle size at similar enzyme loadings ( approximately 8%). From the IR images, the fractions of total surface area available to the enzyme are 21, 33, 35, 37, and 88% for particle sizes 350-600, 120, 75, 35 microm (pore size 300 A), and 35 microm (pore size 1000 A), respectively. Titration with methyl p-nitrophenyl n-hexylphosphate (MNPHP) showed that the fraction of active CALB molecules adsorbed onto resins was approximately 60%. The fraction of active CALB molecules was invariable as a function of resin particle and pore size. At approximately 8% (w/w) CALB loading, by increasing the immobilization support pore diameter from 300 to 1000 A, the turnover frequency (TOF) of epsilon-caprolactone (epsilon-CL) to polyester increased from 12.4 to 28.2 s-1. However, the epsilon-CL conversion rate was not influenced by changes in resin particle size. Similar trends were observed for condensation polymerizations between 1,8-octanediol and adipic acid. The results herein are compared to those obtained with a similar series of methyl methacrylate resins, where variations in particle size largely affected CALB distribution within resins and catalyst activity for polyester synthesis.
Chen
Bo
B
NSF I/UCRC for Biocatalysis and Bioprocessing of Macromolecules, Polytechnic University, 6 Metrotech Center, Brooklyn, New York 11201, USA.
Miller
M Elizabeth
ME
Gross
Richard A
RA
D000327:Adsorption; D002175:Candida / Q000201:enzymology*; D020134:Catalytic Domain; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D005656:Fungal Proteins; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D010316:Particle Size; D011091:Polyesters / Q000378:metabolism*; D011137:Polystyrenes; D012117:Resins, Synthetic; D013055:Spectrophotometry, Infrared
D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D011091:Polyesters; D011137:Polystyrenes; D012117:Resins, Synthetic; D008049:Lipase; C431349:lipase B, Candida antarctica