Lyons J M & Raison J K. A temperature-induced transition in mitochondrial oxidation: contrasts between cold and warm-blooded animals. Comp. Biochem. Physiol. 37:405-11, 1970

00 succinate oxidase activity of liver mitochondria from homeotherms and poikilotherms. For the poikilotherms, Arrhenius-type plots were linear over the temperature range 4°to 30°C. In contrast, for the homeotherms, the plots were biphasic with a ‘break” or “discontinuity” at about 23°Cand an increase in Arrhenius activation energy in the temperature range beiow the “break.” The results suggest that a phase change occurs in membrane lipids of mitochondria from homeotherms, at about 23°C, that alters the thermal properties of the membrane and limits survival of the animal below this temperature. The lack of a phase change in the mitochondria from poikilotherms is consistent with their ability to survive body temperatures near 0°C. [The SC! 5 indicates that this paper has been cited in over 135 publications.1