Binding and elution behavior of proteins on strong cation exchangers.

This work provides a broad survey of binding and elution behavior of proteins on strong cation exchangers. Four proteins comprising two monoclonal antibodies, lysozyme, and cytochrome c were used as models in the investigation. Seven chromatography resins with different base matrices were compared.

Comparison of agarose and dextran-grafted agarose strong ion exchangers for the separation of protein aggregates.

The control of aggregate levels in recombinant protein based drugs is a primary concern during process development and manufacture. In recent years, a novel class of dextran-grafted ion exchange matrices has gained popularity for process scale protein purification due to increased mass transfer rates and higher dynamic binding capacity compared to conventional matrices. Using bovine serum albumin and a monoclonal antibody as model proteins, we studied Sepharose FF and Sepharose XL ion exchangers for the separation of protein aggregates.

Use of the design-of-experiments approach for the development of a refolding technology for progenipoietin-1, a recombinant human cytokine fusion protein from Escherichia coli inclusion bodies.

Optimization of refolding conditions for progenipoietin was performed. The molecule has five disulfide bonds and, hence, is a challenge to refold. Variables studied included pH, DTT (dithiothreitol) concentration, cystine concentration, urea concentration, protein concentration, dissolution hold time and oxygen availability.

Separation of product associating E. coli host cell proteins OppA and DppA from recombinant apolipoprotein A-I(Milano) in an industrial HIC unit operation.

We have shown how product associating E. coli host cell proteins (HCPs) OppA and DppA can be substantially separated from apolipoprotein A-I(Milano) (apo A-I(M)) using Butyl Sepharose hydrophobic interaction chromatography (HIC). This work illustrates the complex problems that frequently arise during development and scale-up of biopharmaceutical manufacturing processes.

Separation of protein charge variants with induced pH gradients using anion exchange chromatographic columns.

This work concerns the chromatographic separation of protein charge variants using pH gradients generated by step changes in buffer composition with weak base anion exchange columns. A local equilibrium model is first developed to describe pH transitions occurring in the column using buffers comprising neutral, zwitterionic or positively charged species. Model predictions, based solely on the resins' titration curves and obtained with the method of characteristics, show, in excellent agreement with experiments, that induced pH gradients of varying durations and shapes can be obtained with a broad range of buffer systems including Tris, Bis-Tris propane, histidine, and their mixtures and ethanolamine.

Separation of recombinant apolipoprotein A-I(Milano) modified forms and aggregates in an industrial ion-exchange chromatography unit operation.

We have shown how protein self-association impacts the ion-exchange separation of modified forms and aggregates for apolipoprotein A-I(Milano). It is well known that reversible self-association of a protein can lead to chromatographic band broadening, peak splitting, merging, fronting, and tailing. To mitigate these effects, urea or an organic modifier can be added to the chromatography buffers to shift the equilibrium distribution of the target molecule to the dissociated form.

Use of cyclohexanedimethanol as a nonflammable organic solvent for industrial scale reversed phase chromatography.

This work demonstrates that cyclohexanedimethanol is an effective nonflammable organic solvent for the pilot scale reversed phase chromatography of recombinant apolipoprotein A-I(Milano). Cyclohexanedimethanol has low viscosity in water, enabling the use of conventional low pressure process scale chromatography columns and hardware. Results from pilot scale manufacturing using a 30 cm diameter CG71M packed column indicate that a 5.

Use of glycol ethers for selective release of periplasmic proteins from Gram-negative bacteria.

Genetic modification of Gram-negative bacteria to express a desired protein within the cell's periplasmic space, located between the inner cytoplasmic membrane and the outer cell wall, can offer an attractive strategy for commercial production of therapeutic proteins and industrial enzymes. In certain applications, the product expression rate is high, and the ability to isolate the product from the cell mass is greatly enhanced because of the product's compartmentalized location within the cell. Protein release methods that increase the permeability of the outer cell wall for primary recovery, but avoid rupturing the inner cell membrane, reduce contamination of the recovered product with other host cell components and simplify final purification.

Evaluation of refolding conditions for a human recombinant fusion cytokine protein, promegapoietin-1a.

Conditions to obtain correctly folded PMP-1a (promegapoietin-1a), an engineered fusion IL-3 (interleukin-3) and thrombopoietin receptor agonist from recombinant Escherichia coli IBs (inclusion bodies), were defined to generate sufficient amounts of protein for evaluation as a potential therapeutic compound. Several ionic and non-ionic detergents, as well as the chaotrope urea, in combination with selected additives, were screened for their ability to dissolve IB protein and promote formation of monomeric, oxidized protein. Upon dissolution, soluble aggregates constituted 50-60% of total protein in detergent-solubilized IBs depending on the level of detergent used, whereas use of urea increased aggregation to approx.

Impact of denaturation with urea on recombinant apolipoprotein A-IMilano ion-exchange adsorption: equilibrium uptake behavior and protein mass transfer kinetics.

We have studied the equilibrium uptake behavior and mass transfer rate of recombinant apolipoprotein A-I(Milano) (apo A-I(M)) on Q Sepharose HP under non-denaturing, partially denaturing, and fully denaturing conditions. The protein of interest in this study is composed of amphipathic alpha helices that serve to solubilize and transport lipids. The dual nature of this molecule leads to the formation of micellar-like structures and self association in solution.

Process characterization of the chromatographic steps in the purification process of a recombinant Escherichia coli-expressed protein.

Process development and characterization studies were performed for the chromatographic steps in the purification process of a recombinant Escherichia coli -expressed protein product candidate. The objective of this work was to develop a robust and efficient purification process that would generate material of adequate purity and quantity. A resin screening procedure was developed to aid in picking out the optimal resin for each of the chromatographic columns.