Abstract:

Phospholipase A2 (PLA2) was used to hydrolyze phosphatidylcholine (PC) in microemulsions. Phase diagrams were constructed for mixts. of alcs. (C2-C6), medium chain triglycerides (tricaprylin, TC) or vegetable oils, PC and water, and areas corresponding to isotropic systems were identified. The PC hydrolysis was carried out with high yields at various PC/(TC+alc.) compns. within the areas of isotropic systems at increasing amts. of solubilized water. The initial reaction rates depended on the aggregation state of the PC (size and nature of microemulsion structures), as well as on temp. and mode of calcium addn. At low enzyme concns., hydrolysis was preceded by a "lag phase" followed by an abrupt increase in rate. By contrast, no latency was obsd. at higher PLA2 PC ratios and the rate was significantly higher. The easy access of the enzyme to the substrate in the curved phospholipid-contg. microemulsion particles facilitate activation of the enzyme and "pushes" the reaction to completion. Hence, these microemulsions can serve as microreactors for the enzymic high yield hydrolysis. [on SciFinder(R)]