STUDY OF FUMARASE ACTIVITY IN NONCONVENTIONAL MEDIA .1.

Fumarase catalysed hydration of fumarate was investigated in water/org anic solvent one-phase systems. The organic solvents used were ethylen e glycol, glycerol and dimethylformamide. The effects of the amount of organic solvent on the maximum velocity (V-max), the Michaelis-Menten constant (K-M) and the equilibrium constant (K-eq) were studied in al l the reaction media. Together with a denaturing power of the solvent evidenced by a systematic decrease of V-max also a surprising decrease of the K-M was registered as the percentage of organic solvent in the reaction media was increased. While the equilibrium constant of the r eaction (K-eq = [L-malate]/[fumarate]) decreased when the percentage o f organic solvent was raised. An interpretation of these facts was giv en. Time-dependent denaturation was also investigated and glycerol res ulted the less denaturing of the solvents used, while the aprotic DMF exhibited the highest deactivation.