Cellulose-based metal chelate-epoxy bifunctional adsorbent for concomitant purification and covalent immobilization of His-tagged trehalose synthase

Title : Cellulose-based metal chelate-epoxy bifunctional adsorbent for concomitant purification and covalent immobilization of His-tagged trehalose synthase

Abstract:

The development and application of cellulose-based metal chelate-epoxy bifunctional adsorbent for the concomitant purification and immobilization of enzymes will be presented. Upon ?-cyclodextrin grafting, the adsorption capacity of the cellulose-based metal chelate adsorbent for the model protein, recombinant His-tagged trehalose synthase, was increased by more than ca. 160% from 6.45 ± 0.01 mg/g to 16.97 ± 0.01 mg/g. While the adsorption capacity of the Ni2+-loaded adsorbent exhibited the highest adsorption capacity of 17.46 ± 0.21 mg/g, the immobilized enzyme prepared with the Zn2+-loaded adsorbent had the highest specific activity, 21.47±0.94 U/g, indicating that Zn2+ had the highest selectivity for the His-tagged trehalose synthase. The adsorption of the model protein essential followed the Langmuir isotherm model. A series of metal chelate-epoxy bifunctional adsorbents with distinct [metal chelate group]/[epoxy group] ratios were prepared by adjusting the reaction time and iminodiacetic acid concentration accordingly. An ideal bifunctional adsorbent should contain both high level of metal chelate groups for selective adsorption of His-tagged protein and enough epoxy groups for the formation of covalent linkages with the adsorbed protein molecules. Although the bifunctional adsorbent with the highest [metal chelate group]/[epoxy group] ratio exhibited the highest metal chelating capacity and adsorption capacity for the enzyme, the lack of epoxy groups limited its utility for the subsequent covalent immobilization of the adsorbed enzyme. The bifunctional adsorbent with a [metal chelate group]/[epoxy group] ratio of 1.20 was found to exhibit a sound protein adsorption capacity of 8.17 mg/g and an immobilization yield of 62.6%. The immobilized enzyme thus prepared exhibited superior operational stability, retaining 90% of the initial activity after 20 cycles, in a repeated-batch process for the conversion of maltose to trehalose. The employment of the metal chelate-epoxy bifunctional adsorbent can significantly facilitate the process of the preparation of immobilized enzymes.
Audience Take Away: 

• Grafting of beta cyclodextrin increased the adsorption capacity of the adsorbent by 162%.
• The bifunctional adsorbent with a [metal chelate group]/[epoxy group] ratio of 1.20 was found to exhibit both a sound protein adsorption capacity and high immobilization yield.
• The immobilized enzyme prepared with the bifunctional adsorbent exhibit superior operational stability in repeated-batch process.
• The employment of the bifunctional adsorbent for concomitant selective adsorption and covalent immobilization can significantly facilitate the process for the preparation of immobilized enzymes.

Biography:

Dr. Lin studied Chemical Engineering at National Cheng Kung University, Taiwan and graduated as BS in 1985. Upon completing the military service, he joined the research group of Prof. George Georgiou at the University of Texas at Austin, USA, where he received his PhD degree in 1993. He joined the Department of Chemical Engineering at National Chung Hsing University, Taiwan as an Associate Professor in 1994. He has published numerous papers in the fields biosurfactants, bioseparations, and enzyme immobilization in SCI journals.