These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Effects of macroporous resin size on Candida antarctica lipase B adsorption, fraction of active molecules, and catalytic activity for polyester synthesis.
    Author: Chen B, Miller EM, Miller L, Maikner JJ, Gross RA.
    Journal: Langmuir; 2007 Jan 30; 23(3):1381-7. PubMed ID: 17241062.
    Abstract:
    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.
    [Abstract] [Full Text] [Related] [New Search]