Stability and Stabilization of Enzymes from Mesophilic and Thermophilic Organisms in Respect to Their Use in FIA-Systems for the Determination ofL-Lactate and Acetate

Abstract

The stabilization effect of ‘bilayer encagement’ on enzymes from mesophilic organisms and their ‘thermophilic’ counterparts was compared. Lactate dehydrogenases from pig heart and from a thermophilic bacterium (Clostridium thermohydrosulfuricum), respectively, showed stabilization factors of 4·5 (at 47°C) and 12·8 (at 70°C), respectively. For ‘thermophilic’ acetate kinase no stabilization effect of encagement was observed. Lactate dehydrogenase and acetate kinase from Clostridium thermohydrosulfuricum were immobilized to controlled porous glass and tested for their long-term stability. The ‘thermophilic’ enzymes showed by far a longer half-life as compared with the corresponding enzymes from pig heart and Escherichia coli, respectively, the half-life time of the flow injection system response with thermophilic lactate dehydrogenase at 35°C attaining 250 h (mesophilic enzyme 89 h), and with thermophilic acetate kinase 79 h (mesophilic enzyme 24 h). © 1997 SCI.