Showing papers by "Theodore W. Randolph published in 2010"

Aggregation of a monoclonal antibody induced by adsorption to stainless steel.

Abstract: Stainless steel is a ubiquitous surface in therapeutic protein production equipment and is also present as the needle in pre-filled syringe biopharmaceutical products. Stainless steel microparticles can cause the aggregation of a monoclonal antibody (mAb). The initial rate of mAb aggregation was second order in steel surface area and zero order in mAb concentration, generally consistent with a bimolecular surface aggregation being the rate-limiting step. Polysorbate 20 (PS20) suppressed the aggregation yet was unable to desorb the firmly bound first layer of protein that adsorbs to the stainless steel surface. Also, there was no exchange of mAb from the first adsorbed layer to the bulk phase, suggesting that the aggregation process actually occurs on subsequent adsorption layers. No oxidized Met residues were detected in the mass spectrum of a digest of a highly aggregated mAb, although there was a fourfold increase in carbonyl groups due to protein oxidation.

Recombinant murine growth hormone from E. coli inclusion bodies: Expression, high-pressure solubilization and refolding, and characterization of activity and structure

Abstract: We expressed recombinant murine growth hormone (rmGH) in E. coli as a cost-effective way to produce large quantities (gram scale) of the protein for use in murine studies of immunogenicity to therapeutic proteins. High hydrostatic pressure was used to achieve high solubility and high refolding yields of rmGH protein produced in E. coli inclusion bodies. A two-step column purification protocol was used to produce 99% pure monomeric rmGH. Secondary and tertiary structures of purified rmGH were investigated using circular dichroism and 2D-UV spectroscopy. The purified rmGH produced was found to be biologically active in hypophysectomized rats.

Crystallization of recombinant human growth hormone at elevated pressures: Pressure effects on PEG-induced volume exclusion interactions

Abstract: Crystallization of recombinant human growth hormone (rhGH) at elevated pressures was investigated in the presence of 6,000 molecular weight poly(ethylene glycol; PEG-6000). Crystallization of rhGH at atmospheric pressure occurred at a protein concentration of 15 mg/mL in 6% PEG-6000. Crystallization did not occur in the same solutions at 250 MPa. In contrast, at a pressure of 250 MPa in the presence of 8% PEG-6000, rhGH readily crystallized from solutions containing 35 mg/mL rhGH, whereas amorphous precipitate formed in the same solutions at atmospheric pressure. Osmotic virial coefficients were determined from static light scattering measurements and combined with a hard-sphere activity coefficient model to predict rhGH activity coefficients as a function of pressure and PEG concentration. Predicted activity coefficients quantitatively matched those determined from equilibrium solubility measurements. The ability to adjust the thermodynamic non-ideality with pressure provides a valuable tool to study protein crystallization in addition to providing a methodology for obtaining crystals at elevated pressures.

High pressure protein crystallization

Abstract: The present disclosure provides an effective method for the crystallization of proteins at high pressure. A preferential excluding agent, and optionally other reagents may be incorporated into the method. The method is applicable to substantially all proteins.