Abstract
Problem statement: The enzyme immobilization has experienced substantial growth in the recent past and an ever increasing amount of study has been reported on various aspects of immobilized enzymes. In most of these investigations, catalytic activities are found to be diminished as compared to the enzyme free in solution. Approach: Hydrophobic adsorbents were prepared containing L-leucine or citric acid, two positive allosteric effectors, for bovine liver Glutamate Dehydrogenase (GDH, EC 1.4.1.3) and heart mitochondrial Malate Dehydrogenase (MDH, EC 1.1.1.37 ), respectively. Results: Immobilized preparations of these well-defined allosteric enzymes indicated improved catalytic activities as compared with those involving use of the adsorbents without these activators. Conclusion/Recommendations: It is concluded that the regulatory proteins are Furthermore; they retain their natural capacity for undergoing the conformational transitions needed for enhanced catalytic activities. Adsorptive immobilization of these two allosteric proteins in activated conformation may serve as useful models in relation to design strategies for preparation of tailor-made enzyme carriers.
Highlights
The science and technology of enzyme immobilization have experienced substantial growth in the recent past and an ever increasing amount of study has been reported on various aspects of immobilized enzymes
An enhanced catalytic activity of the allosteric protein was obtained using the hydrophobic matrix containing L-leucine, presumably as a result of the effector interacting with the protein at its allosteric site
Use of octadecyl groups containing L-alanine: In another control experiment, L-alanine was placed in the middle of the alkyl chain and the derivatized ligand was used to prepare the hydrophobic matrix
Summary
The science and technology of enzyme immobilization have experienced substantial growth in the recent past and an ever increasing amount of study has been reported on various aspects of immobilized enzymes In most of these investigations, catalytic activities are found to be diminished as compared to the enzyme free in solution. Our own previous studies involving use of hydrophobic supports indicated the possibility of protein adsorption with retention of native properties (NematGorgani and Karimian, 1982; 1983; 1984; 1986; NematGorgani et al, 1985). In such studies, bovine liver glutamate dehydrogenase was used as a model allosteric protein and the immobilized preparation was found to retain its response to all of the relevant allosteric modifiers tested, including L-leucine, in addition to retaining its usual catalytic activities. Flexibility of protein structure is maintained and the heterotropic allosteric conformational changes may take place upon interaction of the immobilized enzyme with the effectors
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