Derivative conductometry profile of thermal alterations in cellular membranes—a possible relationship between membrane alterations, cellular proliferation capacity and maximum temperature of growth

Abstract Recording the first derivative of suspension impedance during heating, two alterations have been detected in human erythrocyte membrane at 50°C (A-peak) and 62°C (R-peak). Electric capacitance decreases at the A-peak due to dephosphorylation of peripheral protein spectrin (Gen. Phys. Biophys. 18 (1999) 165). The 62°C membrane alteration activates basal ion permeability in the entire 37–55°C interval (J. Therm. Biol. 24 (1999) 143) causing thermal hemolysis at hyperthermia and apparently reducing the life span of erythrocytes in blood circulation. Here, another membrane alteration was detected at about 37°C (L-peak) related to the activation of phosphate transport via the anion exchanger. Similar alterations were detected in various animal cells, yeast cells, mould spores, and bacteria strains. In NaCl/sucrose media, the L-peak was present only in cells capable of growth and proliferation (Ehrlich ascites tumor cells and young bacteria) that possibly relates this alteration to the proliferation potential of cells. The A-peak was detected only in animal cells that possess spectrin-like peripheral protein. Compared to mammal erythrocytes, the top temperature of A-peak was increased in bird erythrocytes as much as the body temperature in birds was above that in mammals. The R-peak temperature strongly varied depending on cell type; nevertheless, in phsychrophile, mesophile and thermophile bacteria, it was strictly spaced 16–18°C above their maximum growth temperature. Based on previous studies on erythrocytes, the hyperthermic activation of basal permeability in other cells could also be assumed related to the membrane R-alteration that involves a pre-denaturation transition in membrane-embedded domain of integral proteins. A theory is put forward that this is a second order transition similar to the glassy to rubbery state transition that takes place in amorphous materials upon heating.