In situ product removal of ketoses by immobilized 3‐amino phenyl boronic acid: Effect of immobilization method on pH profile

Abstract

The use of polymeric derivatives of phenylboronic acid (PBA) as an effective means for specific in situ product removal of ketoses from aldose-containing reaction mixtures, strongly depends on the retention of selective binding of ketoses exhibited by soluble PBA and 3-amino PBA, by their polymeric, water insoluble analogs. In this communication we demonstrate that immobilization chemistry has a strong effect on ketose preferred binding by polymeric PBA derivatives. Our results indicate that for the preparation of an effective and more specific adsorbent, 3-amino PBA should be coupled to the polymeric carrier via alkylamino chemistry and not via the commonly employed amido derivative. Immobilized alkylamino-PBA exhibited selective fructose and xylulose binding throughout glucose and xylose isomerization processes at the pH range of 7.0-8.0.

Improving process conditions of hydroxytyrosol synthesis by toluene-4-monooxygenase

“…by introducing an electron-withdrawing group) can enable stable complex formation under more favorable pH conditions. This idea was previously applied by Dukler et al for ISPR of a ketose product from aldose-containing medium [18].…”

“…Lorand and Edwards were the first to show that such ester formation is more favorable in solutions of high pH where the boronate ion exists in high concentrations [19]. Following this observation, boronic acid derivatives (RB(OH) 2 ) on various solid supports have been investigated and applied for separation of various compounds, as saccharides, nucleotides and catechols, including l-DOPA, catechol estrogens, and catechol amines [16][17][18]20]. Consequently, beads conjugated with boronic acid residues can be employed for the recovery of HTyr.…”

“…Boric acid gel is a commercial resin, capable of forming a complex with cis-diol groups of various compounds, under neutral or weakly alkaline conditions (resulting with the formation of reversible boronic esters) and releasing them in an acidic solution [16][17][18]. Lorand and Edwards were the first to show that such ester formation is more favorable in solutions of high pH where the boronate ion exists in high concentrations [19].…”

Semi‐continuous enzymatic synthesis of cefaclor enhanced by in situ product removal

“…The yields with ISPR can be enhanced by the following ways: (i) shifting unfavorable reaction equilibria; (ii) minimizing the product loss caused by hydrolysis and (iii) benefiting the downstream processing 3. Product removal could be achieved by an aqueous two‐phase system,2 adsorption,4, 5 affinity,6, 7 evaporation,8 pervaporation,9 or formation of compounds with low solubility 1, 10–13. Some cephalosporin antibiotics, such as cephalexin and cefaclor, can react with naphthol to form insoluble complexes,10–13 which can be used in the synthesis of antibiotics to remove the product from the reaction mixture, and consequently to shift the reaction equilibria to increase the yield.…”

New affine sorbent for determining glycosylated hemoglobin in early diagnostics of carbohydrate metabolism disturbances

“…It was reported that APBA is a potential lipase inhibitor [5]. A column with immobilized APBA was used for testing drugs with respect to the activity of soluble and membrane-bound dopamine b-hydroxylase [6] and for the removal of ketoses from a reaction mixture containing aldose [7]. APBA can provide steric blocking of cell adhesion to biological tissues [8].…”