FIGURE 2.

Immobilization of PDBA-modified protein on SHA-affinity membranes inserted into microcentrifuge spin columns. Disks of SHA-membranes, 5 mm in diameter, were overlayed with 100 μL aliquots of PDBA-AP or unmodified AP in PBS. The protein solutions were passed through the membranes by slow centrifugation. AP activity in the flow-through was analyzed using pNPP (para-nitrophenyl phosphate) and monitoring absorbance at l = 405 nm. Protein concentrations were determined by preparing standard curves of AP at 0 μg/mL, 10 μg/mL, 20 μg/mL, 30 μg/mL, and 40 μg/mL.