Affinity liquid-liquid extraction of lactate dehydrogenase on a large scale.

Rapid liquid-liquid extraction of lactate dehydrogenase from muscle by using a low-cost aqueous bipolymer two-phase system was achieved by using a centrifugal separator. Extraction of the target enzyme into the upper phase was enhanced by including the dye Procion yellow HE-3G (bound to polyethylene glycol). The dye acted as an affinity ligand for the enzyme. The isolation of the enzyme was carried out either by using a cell extract or by homogenizing the muscle directly in the system. The latter approach reduced the preparation time with a factor of 0.25. The two methods gave, respectively, 310 and 360 kU lactate dehydrogenase/kg muscle (measured at 22 degrees C). By using a small centrifugal separator, Alfa Laval LAPX 202, 3-5 kg muscle could be processed/h in a 30-L, two-phase system.