Crystallographic studies on lactate dehydrogenase at –75°C

Abstract

Crystals of lactate dehydrogenase (LDH) were frozen by equilibration in a sucrose-ammonium sulfate solution, and then dipping into liquid nitrogen. The rate of radiation damage for frozen crystals was tenfold less than for crystals at room temperature. The physical properties of frozen crystals are discussed. Analysis of 35 A data collected at -75°C for native LDH and two heavy atom derivatives showed that these derivatives retained their isomorphism in the frozen state.