High-performance hydrophobic interaction chromatography of proteins on a pellicular support based on hydrophilic resin

Hydrophobic interaction chromatography at low salt concentration for the capture of monoclonal antibodies

We evaluated hydrophobic interaction chromatography (HIC) at low salt concentration for the capture of proteins from feed stocks by using monoclonal antibodies as model samples. It was indicated that the HIC at low salt concentration on critical hydrophobicity supports has a potential for capturing hydrophobic monoclonal antibodies directly from large volumes of feed stocks and recovering bound monoclonal antibodies in high yield. On the other hand, the HIC at low salt concentration did not seem so useful for the capture of weakly hydrophobic monoclonal antibodies. The recovery of weakly hydrophobic monoclonal antibodies from columns packed with critical hydrophobicity supports was not quantitative and significantly decreased as the residence time of the monoclonal antibodies in the columns became longer.

Effect of chromatographic conditions on resolution in high-performance ion-exchange chromatography of proteins on nonporous support

We explored chromatographic conditions to obtain high resolution in protein separations by ion-exchange chromatography (IEC) on a nonporous anion-exchange resin of 2.5 microm in particle diameter. We studied the effects of gradient time (steepness of salt concentration gradient), flow-rate and column length on resolution in much wider ranges than had been studied before. It was found that two distinct conditions exist that provide high resolution. The first is a condition which has widely been employed in current high-performance IEC, namely, a combination of short gradient time, high flow-rate and comparatively short column. Separation times are usually 5-30 min, and even more rapid (1-2 min) separations are possible. The second is the condition which has rarely been employed in high-performance IEC. It is a combination of long gradient time, low flow-rate and long column. Although it takes several hours for one separation, very high resolution is attainable.

Hydrophobicity gradient columns for the separation of trypsin inhibitor by hydrophobic interaction chromatography at low salt concentration

We investigated hydrophobicity gradient columns composed of two columns packed with supports of different hydrophobicities in order to save time in protein separation by hydrophobic interaction chromatography at low salt concentration using a crude sample of trypsin inhibitor as a model sample. One of the two hydrophobicity gradient columns was packed with a support whose hydrophobicity was critically controlled for target protein (trypsin inhibitor) and the other was packed with a support which was less hydrophobic than the critically controlled hydrophobicity support. It was found that the hydrophobicity gradient columns are useful to separate samples containing impurities of a wide range of hydrophobicities within a reasonable time.

Separation of proteins by hydrophobic interaction chromatography at low salt concentration

We investigated protein separation by hydrophobic interaction chromatography (HIC) at low salt concentration on the supports of various hydrophobicities. Hydrophobic proteins could be successfully separated with more than 90% recovery by gradient elution of ammonium sulfate from 0.3-0.5 M to 0 in 50 mM phosphate buffer (pH 6.8) by using supports whose hydrophobicities were properly adjusted individually for each protein. Satisfactory results were also obtained by isocratic elution without ammonium sulfate and gradient elution of ethanol from 0 to 10%. HIC at low salt concentration was compatible with other modes of liquid chromatography like ion-exchange chromatography. On the other hand, it was not successful to separate hydrophilic proteins at low salt concentration. Recoveries of hydrophilic proteins decreased before they were retained enough as support hydrophobicity increased. Therefore, it is inevitable to use a higher concentration of salt, e.g., 1-2 M ammonium sulfate, on hydrophilic or moderately hydrophobic support in order to retain hydrophilic proteins without decrease in recovery.

Hydrophobic interaction chromatography of proteins

In this article, an overview of hydrophobic interaction chromatography (HIC) of proteins is given. After a brief description of protein hydrophobicity and hydrophobic interactions, we present the different proposed theories for the retention mechanism of proteins in HIC. Additionally, the main parameters to consider for the optimization of fractionation processes by HIC and the stationary phases available were described. Selected examples of protein fractionation by HIC are also presented.

Hydrophobic interaction chromatography of human serum alpha1-antitrypsin and alpha1-acid glycoprotein

The relative hydrophobicity of human serum alpha1-antitrypsin (AAT) and alpha1-acid glycoprotein (AGP) in comparison to various reference proteins was determined by hydrophobic interaction chromatography (HIC). Apolar character of glycoproteins was generated using three different cosmotropic salts, ammonium sulfate, sodium sulfate, sodium citrate and isocratic, or reversed linear gradient elution techniques. Human serum AAT and AGP showed different apolar properties on Fractogel EMD phenyl and propyl columns modulated either by the type and concentration of cosmotropic salts, or by the pH of the mobile phase. According to its higher carbohydrate content AGP proved to be more polar than AAT. Human serum AAT and AGP were pre-separated by Cibacron Blue F3G-A dye ligand affinity chromatography and based on their different hydrophobicity were fractionated and purified by HIC.

Protein separation using non-porous sorbents

This article overviews the development of non-porous sorbents having small particle diameters which have proven effective for rapid analysis and micropreparative separation of proteins by liquid chromatography. Much attention is given to the preparation and application of silica- and polystyrene-based non-porous packings for various chromatographic modes, especially affinity chromatography. Modeling works on the prediction and parameter estimation for the dynamics of protein adsorption using non-porous sorbents are reviewed and briefly described. To conclude this review, future prospects of the application of non-porous sorbents are also presented.