Use of subzero temperatures and aqueous/organic solvent systems to increase the stability of labile enzymes [proceedings].

The loss of enzyme activity during the process of purification is a major obstacle when unstable enzymes are used. Douzou and co-workers introduced the idea of using chromatography at subzero temperature in aqueous/organic solvent systems (Balny et al.. 1975). In the present paper we describe the apparatus and a method of using an aqueous/ organic solvent system to purify unstable enzymes at subzero temperatures. The nuclear enzyme poly(ADP4bose) polymerase from pig thymus was used, which catalyses the sequential transfer of the ADP-ribose moiety of NAD+ to nuclear proteins [for reviews see Hilz &Stone (1976) and Hayaishi & Ueda (1977)l. I t is a very unstable enzyme, with a half-life of 15-20h at 4°C (Brightwell et al., 1975). A comparatively simple apparatus has been used that can achieve temperatures down to -25°C.