Preparation of Silica Gel-Bonded Amylose through Enzyme-Catalyzed Polymerization and Chiral Recognition Ability of Its Phenylcarbamate Derivative in HPLC

Abstract

Amylose was prepared by enzymatic polymerization of alpha-D-glucose 1-phosphate dipotassium catalyzed by a phosphorylase using two kinds of the primers derived from maltopentaose, and then it was chemically bonded to silica gel to be used as a chiral stationary phase (CSP) in high-performance liquid chromatography. In method I, maltopentaose was first lactonized and allowed to react with (3-aminopropyl)triethoxysilane to form an amide bond. Amylose chains with a desired chain length and a narrow molecular weight distribution were then constructed by the enzymatic polymerization. The resulting amylose bearing a trialkoxysilyl group at the terminal was allowed to react with silica gel for immobilization. In method II, maltopentaose was first oxidized to form a potassium gluconate at the reducing terminal. After the enzymatic polymerization was performed with the potassium gluconate, the amylose end was lactonized to be immobilized to 3-aminopropyl-silanized silica gel through amide bond formation. Two amylose-conjugated silica gels thus obtained were treated with a large excess of 3,5-dimethylphenyl isocyanate to convert hydroxy groups of amylose to corresponding carbamate residues. The CSP derived through method II was superior in chiral recognition to the CSP derived from method I and showed better resolving power and higher durability against solvents such as tetrahydrofuran compared with a coated-type CSP. Influences of degree of polymerization of amylose, the spacer length between amylose and silica gel, and mobile phase compositions on chiral recognition were investigated.

Chiral separation by chromatographic and electromigration techniques. A Review

“…A drawback of coated-type phases is the solubility of the cellulose derivatives in some solvents. To improve stability of CTPC-and ATPC-based phases, regioselective chemical bonding of the selector to aminopropyl-silanized silica gel via a diisocyanate spacer was carried out [116][117][118]. A slightly lower chiral recognition compared to the coated-type phases was observed with these CSPs.…”

“…Oliveros et al [119] published a procedure for covalent binding by polymerization of mixed polysaccharide derivatives containing a 3,5-dimethylphenylcarbamate group and a 10-undecenoate spacer. Enomoto et al [117] described the immobilization of amylose to silica by reducing the terminal residue of each molecule involving an enzymatic polymerization of a-d-glucose-1-phosphate. Recently, approaches for fixation based on photochemical and thermal treatment have been patented [120].…”

Immobilized Polysaccharide-Based Chiral Stationary Phases for HPLC

“…59,60 This immobilization method consists of two steps; 59 firstly, amylose was prepared by the enzymatic polymerization of -D-glucose 1-phosphate dipotassium catalyzed by a potato phosphorylase using two kinds of primers derived from maltopentaose. [61][62][63] The amylose chains, which have a desired chain length and a narrow molecular mass distribution, are then bonded to silica gel to be used as CSPs.…”

Enantioseparation on Riboflavin Derivatives Chemically Bonded to Silica Gel as Chiral Stationary Phases for HPLC

“…21 These results suggest that riboflavin and its derivatives may have the potential as promising CSPs for separation of polyaromatic racemic compounds through - interactions including charge-transfer complexation between the analytes and isoalloxazine ring of the riboflavin 20 when they are chemically-bonded to silica gel. [22][23][24][25] Riboflavin has reactive hydroxy and amino groups, and modification with various substituents and further chemical bonding to silica gel are possible.…”