A rapid controller of temperature for use in determining Arrhenius profiles in biomembrane systems.

To minimize artifacts in temperature-velocity (Arrhenius) profiles due to aging of preparations of biological membranes, a rapid controller of temperature was developed for spectrophotometric or polarographic (02 electrode) measurements. The reaction mixture is cooled or heated through contact with Peltier elements. One Pt temperature sensor in the cuvette or electrode holder controls current flow into the Peltier units, and another Pt temperature sensor in the reaction mixture is used to read out the sample temperature on a meter or recorder, and to provide feedback control. The sample temperature can be reproducibly set to within 0.1 degree C, with a noise level of 0.04 degrees C or less; a change of 4 degrees C takes 1 min.