Purification of Penicillin G Amidase using quaternary ammonium salts and effect on the activity of the immobilised enzymes

This paper describes the purification of Penicillin G Amidase (EC 3.5.1.11) using quaternary ammonium salts with the aim of increasing the activity of immobilised enzymes prepared from the purified solutions. Two different quaternary ammonium salts were tested with different solutions of the enzyme. It was concluded that the quaternary ammonium salts used selectively precipitated the non-enzymatic protein leaving in solution practically all the enzyme resulting in a high yield of purification. Optimal conditions for purification using the two types of quaternary ammonium salts were determined. Immobilisation studies were performed from various purified enzyme solutions, using different amounts of a quaternary ammonium salt. The immobilised enzymes so obtained showed a much higher activity than the immobilised enzyme obtained from non-purified enzyme solutions.