Biocatalysis of silica gel-immobilized chlorophyllase in a ternary micellar system

Capillary coating as an important factor in optimization of the off-line and on-line MEKC assays of the highly hydrophobic enzyme chlorophyllase

The choice between bare and coated capillaries is a key decision in the development and use of any methods based on capillary electrophoresis. In this work several permanently and dynamically coated capillaries were successfully implemented in a previously developed micellar electrokinetic chromatography (MEKC) assay of the plant membrane enzyme chlorophyllase. The results obtained demonstrate the rationale behind the use of capillary coating, which is crucial for successful optimization of both the off-line mode and the on-line/electrophoretically mediated microanalysis assay mode. The application of an amine permanently coated capillary (eCAP) is a simple way to significantly increase the repeatability of migration times and peak areas, and to ensure a strong electroosmotic flow that considerably decreases the overall analysis time. A dynamic coating (CEofix) allows one to apply an on-line incubation to control the reaction progress inside the capillary, and to increase the signal-to-noise ratio and peak efficiency. The dynamic coating is possible with use of both the normally applied uncoated silica capillary and the precoated amine capillary, which ensures more repeatable migration times. The strong points of the uncoated silica capillary are its attractive price and wide range of pH that can be applied. The characteristics presented may simplify the choice of capillary modification, especially in the case of hydrophobic analytes, MEKC-based separations, and other enzymatic assays.

Immobilization and biocatalysis of chlorophyllase in selected organic solvent systems

Chlorophyllase extract from Phaeodactylum tricornutum was immobilized by physical adsorption on DEAE-cellulose and silica gel as well as by covalent binding on Eupergit C, Eupergit C250L, Eupergit C/ethylenediamine (EDA) and Eupergit C250L/EDA. Although the highest immobilization yield (83-93%) and efficiency (51-53%) were obtained when chlorophyllase extract was immobilized on DEAE-cellulose and silica gel, there was no improvement in the thermal stability of chlorophyllase as compared to that of the free one. The immobilization of chlorophyllase extract on Eupergit C250L/EDA resulted by a high recovery of enzymatic activity, with an immobilization efficiency of 44%, and promoted a higher stabilization of chlorophyllase (four times) in the aqueous/miscible organic solvent medium. On the other hand, the inhibitory effect of refined bleached deodorized (RBD) canola oil was reduced by immobilization of chlorophyllase extract onto silica gel as compared to those obtained with other enzyme preparations. However, the re-cycled chlorophyllase extract immobilized on Eupergit C250L/EDA retained more than 75% of its initial enzyme activity after 6 cycles, whereas that immobilized on silica gel was completely inactivated. The highest catalytic efficiency, for both free and immobilized chlorophyllase on Eupergit C250L/EDA, was obtained in the ternary micellar system as compared to the aqueous/miscible organic solvent and biphasic media.