Adsoptive immobilization of glutamate dehydrogenase in allosterically-activated conformation

Intoduction. Allosteric enzymes, in adcittion to their active site, contain sites for the binding of positive and negative effector molecules which regulate the enzyme's activity. In this research, the enzyme glutamate dehydrogenase (GDH) taken from bovine liver, has been chosen as an allosteric model. In previous studies this enzyme was immobilized on hexadecyl fractosil while not only maintaining its catalytic activity but also capable of responding to various effectors. The aims of this study were to examine the immobilization of GDH on different matrixes and the effect of PH on the activity of the free and immobilized enzyme. Material and Methods. Matrixes carrying a variety of ligands such as L-leucine, D-leucine L-alanine were synthesized where upon the immobilization of GDH was investigated. Meanwhile the effect of PH on the activity of the free and immobilized enzyme (in the presence and absence of L-leucine was studied. Results. The enzyme was immobilized in an active conformation and in the presence of a positive effector. In all the pH values tested, a higher acitvity was obtained using preparations containing palmityl grioups substituted with L-leucine. Conclusion. It is cincluded that the allosteric enzyme is immobilized with the effector interacting at its allosteric site. The immobilized preparation may be used in continuos catalytic transformations