Synthesis of sulfonamide- and sulfonyl-phenylboronic acid-modified silica phases for boronate affinity chromatography at physiological pH

Abstract

Two new types of boronate affinity solid phases were synthesized and characterized. The materials were prepared by silylation of porous silica gel with monochlorosilane derivatives containing synthetic sulfonyl-and sulfonamide-substituted phenylboronic acids. The new solid phases were evaluated for boronate affinity chromatography with aryl and alkyl cis-diol compounds, and found suitable for the retention of cis-diols under acidic conditions. Significant correlations between the retention factor (K) and the pH of the mobile phase demonstrate that the binding of cis-diols to the solid phases is best rationalized by chelation. Based on the low ionization constant, caused by the electron-withdrawing effects of the sulfonyl and sulfonamide groups, these media display an enhanced affinity for cis-diols as compared to unsubstituted phenylboronic acid. Utilizing Isocratic elution, a mixture of various biologically relevant L-tyrosines, L-DOPA and several catecholamines were resolved with a mobile phase composed of 0.05 M, pH5.5 phosphate buffer. Mono-, di-and triphosphates of adenosine were also separated at pH 6.0. Hence, the new boronate solid phase offers efficient affinity separation and purification of cis-diol containg molecules under rather mild pH regions.

One-step synthesis of boronic acid group modified silica particles by the aid of epoxy silanes

“…At present, the boronic acid group modified silica synthesis was usually carried out with the aid of organosilane [5][6][7][8][9][10]. Two methods were widely applied, one was the "grafting first and then modification" [6,[11][12][13][14], the other was the "modification first and then grafting" [15][16][17]. In the first method, epoxy silane was grafted on the surface of silica.…”

Synthesis and application of novel phenylboronate affinity materials based on organic polymer particles for selective trapping of glycoproteins

“…In order to facilitate or actually enable boronate affinity chromatography of diols that are poorly stable under alkaline conditions such as catechols, PBA derivatives with lowered pK a -values have been synthesized by introducing electron-withdrawing groups into the phenyl ring, e.g., carboxyl-, nitro-, sulfonyl-, or sulfonamidogroups [13,20,21]. With these substituted PBAs binding of diols was achieved under neutral and even slightly acidic conditions.…”

Advances in purification and separation of posttranslationally modified proteins

“…Several derivatives of boronic acid have been introduced for this purpose, including bisboronic compounds, which can also be conjugated with a fluorescence tag and used for detecting protein glycosylation/glycation [194], and both sulfonyl-and sulfonamide-phenylboronic acid derivatives, which can be used at physiological pH. These adjustments have solved the major drawback of the original setup; the need to use alkaline buffers due to the relatively low ionization constants of the commonly used phenylboronic acid ligands [195]. Non-specific boronate affinity has also been successfully combined with lectin affinity in boronic acid-lectin affinity chromatography [196].…”