Trypsin Immobilization on Derivatized Cellulose Beads by Biospecific Avidin-Biotin Interaction and Characterization of the Immobilized Activity1

Trypsin was immobilized on cellulose beads using the biospecific and high affinity avidin-biotin interaction. Trypsin and cellulose beads were biotinylated with sulfosuccinimidyl-6-(biotinamido) hexanoate (NHS-LC-biotin). Avidin and biotinylated trypsin were sequentially adsorbed to the biotinylated cellulose beads. A similar procedure was carried out using controlled-pore glass (CPG) beads. The properties of the two trypsin bioreactors were examined and compared. The substrate used for the assay of trypsin activity was p-tosyl-L-arginine methyl ester and the extent of biotinylation of biotinylated trypsin and of immobilized biotin on cellulose beads and on CPG beads were determined using the 2-[4′-hydroxyazobenzene]benzoic acid dye-binding method. Biotinylated trypsin in solution retained about 82% of the specific activity of native trypsin. Cellulose beads contained 0.184 μmol/mL (1.15 μmol/g) biotin and CPG beads, 0.329 μmol/mL (0.987 μmol/g). After regeneration, the biotin contents became slightly lower, namely, 0,159 μmol/mL for cellulose beads and 0.315 μmol/mL for CPG beads. The specific activities of trypsin immobilized on cellulose beads and CPG beads were 32 U/mL (202 U/g) and 43 U/mL (130 U/g), respectively. These studies indicate that cellulose beads can be biotinylated for use as bioselective support.