István Mazsaroff

Thermodynamic model for electrostatic-interaction chromatography of proteins

A thermodynamic model derived by Record et al. [M. T. Record, Jr., Biopolymers, 14 (1975) 2137 and M. T. Record, Jr., C. F. Anderson and T. M. Lohman, Q. Rev. Biophys., 11 (1978) 103] from Wymans linkage theory [J. Wyman, Adv. Protein Chem., 19 (1964) 223] using Mannings condensation model [J. Manning, J. Chem. Phys., 51 (1969) 924] was extended to electrostatic interaction chromatography. Mixed, electrostatic and hydrophobic interactions of a model protein, ovalbumin were characterized by ion and water release.

Effects of large sample loads on column lifetime in preparative-scale liquid chromatography

In preparative-scale liquid chromatography of proteins, the use of high sample concentration and large sample mass may result in irreversible adsorption to the support surface. This can change the stationary phase characteristics, reduce the capacity, shorten the column lifetime and diminish the economic viability of a particular separation method. Column recycling and regeneration can influence the throughput (mass purified per time unit) and selectivity, and affect the reproducibility. The effects of large sample loads on column lifetime and performance were evaluated for three strong anion-exchange columns: (1) a silica support with a quaternized polyethyleneimine (PEI) coating, (2) a polymeric support with an adsorbed PEI coating which also was quaternized, and (3) a polymeric support with a proprietary quaternary amine stationary phase. The column capacity for proteins was measured by frontal chromatography and monitored as a function of cycle number. The column lifetime was determined by examining chromatographic properties subsequent to the frontal chromatography. The change in protein binding capacity was then compared to the change in nitrate binding capacity. The column performance was evaluated under analytical conditions by measuring the change in resolution of standard protein mixtures.

Molecular orientation of immunoglobulin G at high concentration on an ion-exchange sorbent

The change of molecular orientation of IgG, bound on a strong-anion-exchange surface, was studied using a generalization of the stoichiometric displacement model, over the entire range of protein adsorption isotherms. The Z number was found to decrease with increasing stationary phase protein concentration, approaching a limiting value. The analogy of the multiple equilibria model within highly cooperative identical binding sites was suggested as a possible way to evaluate the observed change in Z number with the protein concentration.

An Economic Analysis of Performance in Preparative Chromatography of Proteins

Abstract An economic analysis of preparative chromatography of proteins is reported. We present a way to calculate and optimize the efficiency for isolating a desired protein from a given protein mixture with regard to feed, fractionation, product purity, throughput, and operating costs. Evaluation of the overall efficiency for the purification in subsequent steps is also demonstrated.

Phase ratio determination in an ion-exchange column having pores partially accessible to proteins

A method is suggested for determination of the hold-up volume and the phase ratio of a protein on a strong anion-exchange chromatographic column, which is based on mercury porosimetry and size-exclusion calibration with polymer samples.

Performance and economics in micropreparative capillary electrophoresis of oligosaccharides

The advantages of micropreparative capillary gel electrophoresis include very high resolution, high speed and good recovery, with full automation. Nanomolar quantities of biopolymers, such as complex carbohydrates, can be collected for use in subsequent microsequencing or mass spectrometry. As in other preparative separation processes, the goal in preparative capillary gel electrophoresis is to maximize the production of a product with a given purity in the shortest time, i.e., to achieve the highest throughput. Another important factor is the economics of the operation. The cost of production in preparative capillary electrophoresis is a function of the cost of the automated system, the loading capacity of the capillary column and the system cycle time. Here we suggest a simple economic model for analyzing the economics of preparative capillary electrophoresis.