A new method to determine enzyme activities in two-phase systems by Flow Injection Analysis (FIA)

The activity of phospholipase D (PLD) from Streptomyces chromofuscus in two-phase systems consisting of a PLD containing aqueous phase and a phosphatidylcholine (PC) containing organic solvent phase was investigated. Two-phase systems with highly reproducible segmentation were generated in a continuous flow system using a capillary segmentor. Between 0.01 and 2 U/ml PLD from Streptomyces chromofuscus were detected in a water/hexane two-phase system. The linear detection range was 0.01 to 0.5 U PLD/ml. The apparent K-M of Streptomyces chromofuscus PLD in a water/hexane system was 41.43 mu M PC, the apparent V-max was 3.68 mu mole/min mg. The variation of PLD activity in different organic solvents correlated with the solvent's hydrophobicity. If anionic detergents or primary alcohols were added to the two-phase system, concentration dependent activation of the PLD was observed. (C) 1998 Elsevier Science S.A. All rights reserved.