CYCLOHEXIMIDE INCREASES THE THERMOSTABILITY OF PROTEINS IN CHINESE-HAMSTER OVARY CELLS

Protein denaturation resulting from temperatures between 42.0°C and 50°C has been observed and implicated as the lethal lesion for hyperthermic cell killing. A logical corollary is that protection against hyperthemic killing requires stabilization of cellular proteins against thermal denaturation. To test this, Chinese hamster ovary cells were treated with the heat protector cycloheximide and then subjected to differential scanning calorimetry to measure protein denaturation. Cycloheximide stabilized proteins that denatured between 42°C and 52°C in control cells by increasing their transition (denaturation) temperature by an average of 1.3°C. In addition, cycloheximide reduced the cytotoxicity of actinomycin D and adriamycin, suggesting that protein stabilization protects cells against stresses other than hyperthermia. © 1991.