Influence of a soluble anionic polymer on the electrophoresis of proteins

Hydrogels in Electrophoresis: Applications and Advances

A hydrogel is a solid form of polymer network absorbed in a substantial amount of aqueous solution. In electrophoresis, hydrogels play versatile roles including as support media, sieving matrixes, affinity scaffolds, and compositions of molecularly imprinting polymers. Recently, the study of hydrogels has been advancing with unprecedented speed, and the application of hydrogels in separation science has brought new opportunities and possible breakthroughs. A good understanding about the roles and effects of the material is essential for hydrogel applications. This review summarizes the hydrogels that has been described in various modes of electrophoretic separations, including isoelectric focusing gel electrophoresis (IEFGE), isotachophoresis (ITP), gel electrophoresis and affinity gel electrophoresis (AGE). As microchip electrophoresis (ME) is one of the future trends in electrophoresis, thought provoking studies related to hydrogels in ME are also introduced. Novel hydrogels and methods that improve separation performance, facilitate the experimental operation process, allow for rapid analysis, and promote the integration to microfluidic devices are highlighted.

Quantitative evaluation of lectin-reactive glycoforms of α(1)-acid glycoprotein using lectin affinity capillary electrophoresis with fluorescence detection

α(1)-Acid glycoprotein (AGP) was previously shown to be a marker candidate of disease progression and prognosis of patients with malignancies by analysis of its glycoforms via lectins. Herein, affinity capillary electrophoresis of fluorescein-labeled AGP using lectins with the aid of laser-induced fluorescence detection was developed for quantitative evaluation of the fractional ratios of concanavalin A-reactive or Aleuria aurantia lectin-reactive AGP. Labeled AGP was applied at the anodic end of a fused-silica capillary (50 μm id, 360 μm od, 27 cm long) coated with linear polyacryloyl-β-alanyl-β-alanine, and electrophoresis was carried out for about 10 min in 60 mM 3-morpholinopropane-1-sulfonic acid-NaOH buffer (pH 7.35). Addition of the lectins to the anode buffer resulted in the separation of lectin-reactive glycoform peaks from lectin-non-reactive glycoform peaks. Quantification of the peak area of each group revealed that the percent of lectin-reactive AGP is independent of a labeling ratio ranging from 0.4 to 1.5 mol fluorescein/mol AGP, i.e. the standard deviation of 0.5% for an average of 59.9% (n=3). In combination with a facile procedure for micro-purification of AGP from serum, the present procedure, marking the reactivity of AGP with lectins, should be useful in determining the prognosis for a large number of patients with malignancies.

Progress in affinophoresis

The use of polyionic polymers as mobile affinity matrices in electrophoresis has led to the development of a specific separation method for biological substances, affinophoresis. The conjugate of a polyionic polymer and an affinity ligand is called an affinophore. Electrophoresis of proteins in the presence of an affinophore results in a change in the mobility of a specific protein due to the difference between the mobility of the protein and that of the protein-affinophore complex. Polylysine is useful as a base polymer of affinophores and has been used successfully as an anionic matrix after succinylation. Affinophoresis of proteases, lectins and antibodies has been carried out in agarose gel and the mobility of the protein having affinity to each ligand was specifically changed. Two-dimensional affinophoresis, in which an affinophore was included only in the second-dimensional electrophoresis, was effective for the separation of the components of a complex mixture of proteins even if the change of mobility was not large. Red blood cells were successively treated with homologous antiserum, biotinylated second antibody, avidin and biotinylated succinylpolylysine as an affinophore. Specific acceleration of the homologous cells to the antiserum was observed even when the affinophoresis was applied to mixed red blood cells from different species.