Large flexibility of dihydrofolate reductase as revealed by temperature effects on the volume and compressibility

The partial specific volume and adiabatic compressibility of dihydrofolate reductase (DHFR) from Escherichia coli remarkably increased as temperature was higher, corresponding to the conformational changes as revealed by spec troscopic measurements. These results demonstrate that this protein has a h ighly flexible structure at the native state whose tertiary structure or hy drophobic core is easily expanded with temperature to produce the internal cavities.