[Lactate biosensor and energy supply for the enzyme molecule]

A biosensor of lactate has been constructed, made, and tested. The lactate biosensor uses the lactate dehydrogenase molecules from muscle. The lactate biosensor works according to the simplest scheme. An immobilized lactate dehydrogenase molecule binds a L-lactate molecule in the absence of the coenzyme NAD+. Then the L-lactate molecule is oxidized by the electric field of a metal electrode of the biosensor to generate an electron. The transfer of this electron between the immobilized lactate dehydrogenase molecule and the metal electrode of the biosensor is carried out without a redox mediator molecule. A new mechanism for the energy supply of the enzyme molecule is proposed to explain this effect. The new mechanism is based on the electric dipole-dipole interactions occurring in the enzyme molecule and surrounding water and on the thermal energy of this water.