Roles of interstitial fraction and load conditions on the dynamic binding capacity of proteins on capillary-channeled polymer fiber columns.
Capillary-channeled polymer (C-CP) fibers are used as a stationary phase for ion-exchange chromatography of proteins. Collinear packing of the fibers permits operation at high linear velocities (Uo  > 100 mm s(-1)) and low backpressure (<2,000 psi) on analytical-scale columns. Rapid solvent transport is matched with very efficient solute mass transfer as fibers are virtually non-porous with respect to the size of the target protein molecules. Lack of porosity of course limits the equilibrium binding capacity of stationary phases. Breakthrough curves and frontal analysis are used to better understand trade-offs between the kinetic and thermodynamic properties as C-CP fibers are applied in preparative situations. Fiber columns packed to different interstitial fraction values affect both the total fiber surface area (e.g., equilibrium binding capacity [EBC]) and the permittivity to flow and mass transport characteristics (e.g., dynamic binding capacity [DBC]). The EBC of the nylon 6 C-CP fibers was found to be 1.30 mg g(-1), with isotherms that were best matched by a Moreau model, showing linearity up to solute concentrations of ∼0.4 mg mL(-1). Isotherms generated under flow conditions were equally well approximated using Langmuir, Freundlich, and Moreau isotherm models. Fairly linear responses were seen up to the maximum load concentration of 1.2 mg mL(-1). Counterintuitively, dynamic studies revealed that conditions of high column porosity yielded a DBC that is ∼70% higher than the EBC. These findings point to potential advantages in terms downstream processing applications, where protein throughput and yield are critical metrics.
Dept. of Chemistry, Clemson University, Biosystems Research Complex, Clemson, SC, 29631.
Zhengxin
Z
Wang
R Kenneth
RK
Marcus
D000818:Animals; D002417:Cattle; D002852:Chromatography, Ion Exchange / Q000295:instrumentation / Q000379:methods*; D007700:Kinetics; D008956:Models, Chemical; D011108:Polymers / Q000737:chemistry* / Q000378:metabolism*; D016062:Porosity; D011312:Pressure; D011485:Protein Binding; D011506:Proteins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D012710:Serum Albumin, Bovine; D013816:Thermodynamics
D011108:Polymers; D011506:Proteins; D012710:Serum Albumin, Bovine
capillary-channeled polymer; downstream processing; fiber; loading capacity; protein