Immobilization of enzymes using non-ionic colloidal liquid aphrons (CLAs): Activity kinetics, conformation, and energetics.
This study seeks to examine the ability of non-ionic/non-polar Colloidial Liquid Aphrons (CLAs) to preserve enzyme functionality upon immobilization and release. CLAs consisting of micron-sized oil droplets surrounded by a thin aqueous layer stabilized by a mixture of surfactants, were formulated by direct addition (pre-manufacture addition) using 1% Tween 80/mineral oil and 1% Tween 20 and the enzymes lipase, aprotinin and α-chymotrypsin. The results of activity assays for both lipase and α-chymotrypsin showed that kinetic activity increased upon immobilization by factors of 7 and 5.5, respectively, while aprotinin retained approximately 85% of its native activity. The conformation of the enzymes released through desorption showed no significant alterations compared to their native state. Changes in pH and temperature showed that optimum conditions did not change after immobilization, while analysis of activation energy for the immobilized enzyme showed an increase in activity at higher temperatures. Furthermore, the effect of bound water within the aphron structure allowed for some degree of enzyme hydration, and this hydration was needed for an active conformation with results showing a decrease in ΔH* for the immobilized system compared to its native counterpart.
Department of Chemical Engineering, Imperial College London, SW7 2AZ, London, United Kingdom.
Keeran
K
Ward
Department of Chemical Engineering, Imperial College London, SW7 2AZ, London, United Kingdom.
Jingshu
J
Xi
Department of Chemical Engineering, Imperial College London, SW7 2AZ, London, United Kingdom. d.stuckey@imperial.ac.uk.
David C
DC
Stuckey
D000818:Animals; D001234:Aspergillus niger / Q000737:chemistry / Q000201:enzymology*; D002417:Cattle; D002918:Chymotrypsin / Q000737:chemistry / Q000378:metabolism*; D003102:Colloids / Q000737:chemistry*; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D008899:Mineral Oil / Q000737:chemistry*; D011136:Polysorbates / Q000737:chemistry*; D011487:Protein Conformation; D013501:Surface-Active Agents / Q000737:chemistry; D013816:Thermodynamics
D003102:Colloids; D004800:Enzymes, Immobilized; D011136:Polysorbates; D013501:Surface-Active Agents; D008899:Mineral Oil; D008049:Lipase; D002918:Chymotrypsin; C117608:alpha-chymotrypsin
CLA immobilization; enzyme activity; hydration; superactivity; thermodynamics