Minicolumns for affinity chromatography

Determination of fibrinogen in plasma by high-performance immunoaffinity chromatography

A high-performance immunoaffinity chromatographic (HPIAC) method for fibrinogen was developed which had several advantages over existing methodologies including increased linear range and no interference from heparin. Several modifications of usual HPIAC procedures were necessary including the employment of a methacrylate polymeric support to reduce non-specific adsorption and the addition of urea to a pH 2.1 elution buffer to affect elution. A significant split-peak effect (i.e., unretained fibrinogen) was noted at higher flow-rates and at higher fibrinogen concentrations, which was shown to be temperature-dependent, with the amount of fibrinogen retained on the column increasing with increased temperature.

Separation of carbohydrates and lectins on carbohydrate-immobilized resins

A few carbohydrate-immobilized resins were prepared by coupling glycamines of mono- and disaccharides to an epoxy-activated methacrylate base, and the elution profiles of various carbohydrates and lectins from columns packed with the resultant resins were compared. The introduction of glucamine, maltamine or lactamine to the methacrylate base had little effect on the separation of stereoisomers of aldoses, though it enabled group separation of pentoses as well as 6-deoxyhexoses from hexoses. On the other hand, the maltamine-immobilized resin showed strong specific affinity for concanavalin A, as well as lentil and pea lectins. The lactamine-immobilized resin was specific to ricinus agglutinin, peanut agglutinin and soy bean agglutinin. These carbohydrate-immobilized resins were also useful for the isolation of a lectin-like substance from rat liver.

Silica containing primary hydroxyl groups for high-performance affinity chromatography

Primary hydroxyl groups were incorporated into silica by a four-step reaction procedure which includes modification of the silica surface with gamma-glycidoxypropyltrimethoxysilane, leading to an epoxide silica; hydrolysis with acid to yield a diol silica; oxidation of the diol silica with periodate to yield a silica resin with aldehyde functions; and reduction with sodium borohydride to obtain the primary hydroxyl-containing silica. The hydroxyl groups were activated with chloroformates or carbodiimidazole. Proteins were coupled under mild conditions in high yield to these activated silica resins. Columns containing these newly developed silica derivatives were used for the fast and efficient purification of antibodies on antigen-containing silica, as well as for the purification of trypsin on a trypsin inhibitor column (or vice-versa). The effect of pressure on association and dissociation of the affinity complex is discussed.

Profiling of carbohydrates, glycoproteins and glycolipids

Current chromatographic methods for the analysis of a variety of carbohydrate materials in body fluids and tissues have been reviewed, from the viewpoints of clean-up of samples, separation modes, methods for detection and quantification, and degree of convenience. This review also contains several tables, listing names of samples, methods of analysis, analytical conditions, and normal as well as pathological levels reported, from representative publications.

High-performance liquid chromatography column length designed for submicrogram scale protein isolation

High-performance liquid chromatography of small amounts of protein was readdressed with respect to current gas-phase sequencing technology. Useful primary sequence information can be obtained from as little as 5-100 pmol of material. This corresponds on a mass level to the nanogram to microgram range where, unfortunately, HPLC columns often give low recoveries depending on the size and surface hydrophobicity of the peptide or protein. It was rationalized in this study that reduced column length could have a beneficial effect on recovery without significant loss of resolution. To demonstrate this, six HPLC columns ranging from 0.2 to 25 cm in length were made and evaluated in terms of protein loading and resolution. Column lengths of less than 1 cm were found to increase recovery of surface hydrophobic proteins without loss of resolution, as shown for a standard protein profile. These columns resolve proteins best when loaded with less than 10 micrograms, with recoveries greater than 90%. All column internal diameters were at least 4.1 mm so that standard HPLC pumps could be used to generate gradients.

Protein separations on reversed-phase high-performance liquid chromatography minicolumns

The resolution of cytochrome c, bovine serum albumin and ovalbumin on reversed-phase columns under gradient elution conditions was found to be constant or to improve as column length was decreased from 45 to 6.3 mm. The resolution remained constant even when the column length decreased to 1.6 mm. Recovery of protein in the first gradient cycle was improved by the use of short columns.