Fast dissociation of phe-tRNA synthetase from Aspergillus nidulans immobilized on sepharose-6B column by NaCl

Phenylalanyl-tRNA2) synthetase from Aspergillus nidulans was efficiently immobilised to sepharose 6B column containing phenylalanine as the ligand. NaCl was found to be a potent dissociating agent for the immobilised enzyme. While 0.5 M NaCl in discontinuous elution showed a slow impetus on dissociation giving a plateaux profile, a solution of 0.8 M NaCl made the elution rapid giving a sharp peak. On the other hand, in a gradient (continuous) elution the rapidity of dissociation was found to be enhanced with the increase in the difference of the two concentrations. The result suggests that Na+ ions interact with the protein binding site of the ligand eventually dissociating the enzyme molecule by disrupting the covalent bond without affecting its normal catalytic activity.