Pressure dependence of activity and stability of dihydrofolate reductases of the deep-sea bacterium Moritella profunda and Escherichia coli

► We studied the effects of pressure on deep-sea DHFR of Moritella profunda (mpDHFR). ► Enzyme activity of mpDHFR was optimal at 50 MPa. ► mpDHFR is resistant to heat but sensitive to pressure and urea. ► Volume change due to unfolding of mpDHFR is smaller than that of DHFR of E. coli. ► The cavity and surface hydration dominantly contribute to the stability of mpDHFR.