BIOCONVERSION OF PHOSPHOLIPIDS BY IMMOBILIZED PHOSPHOLIPASE A(2)

Phospholipase A(2) selectively hydrolyses the ester linkage at the sn-2 position of phospholipids forming lysocompounds. This bioconversion has importance in biotechnology since lysophospholipids are strong bioemulsifiers. The aim of the present work was to study the kinetic behaviour and properties of immobilized phospholipase A(2) from bee venom adsorbed into an ion exchange support. The enzyme had high affinity for CM-Sephadex(R) support and the non-covalent interaction was optimum at pH 8. The activity of immobilized phospholipase A(2) was comparatively evaluated with the soluble enzyme using a phospholipid/Triton X-100 mixed micelle as assay system. The immobilized enzyme showed high retention activity and excellent stability under storage. The activity of the immobilized system remained almost constant after several cycles of hydrolysis. Immobilized phospholipase A(2) was less sensitive to pH changes compared to soluble form. The kinetic parameters obtained (V-max 883.4 mu mol mg(-1) min(-1) and a KM 12.9 mM for soluble form and V-max = 306 mu mol mg(-1) min(-1) and a KM = 3.9 for immobilized phospholipase A(2)) were in agreement with the immobilization effect. The results obtained with CM-Sephadex(R) - phospholipase A(2) system give a good framework for the development of a continuous phospholipid bioconversion process.