Effects of extremely low frequency electromagnetic fields on membrane-associated enzymes.

The eVects of extremely low frequency electromagnetic Welds of 75Hz were studied on diVerent membrane-associated enzymes. Only the activities of three enzymes out of seven exposed to the Weld decreased approximately of about 54–61% with Weld amplitudes above a threshold of 73–151 T depending on the enzyme. The same Weld had no eVect on the activities of either integral membrane enzymes such as Ca,ATPase, Na/K,ATPase, and succinic dehydrogenase or peripheral membrane enzymes such as photoreceptor PDE. The decrease in enzymatic activity of the Weld-sensitive enzymes was independent of the time of permanence in the Weld and was completely reversible. When these enzymes were solubilized with Triton, no eVect of the Weld was obtained on the enzymatic activity, suggesting the crucial role of the membrane in determining the conditions for enzyme inactivation. The role of the particular linkage of the Weld-sensitive enzymes to the membranes is also discussed.