Phospholipase A In The Aqueous Solution Of Vesicles <sub> 2 </ Sub> Hydrolysis Of Lecithin Reaction

An improved method for investigating the hydrolysis of phospholipase A₂ (PLA2, phosphatide 2-acyl-hydrolase, EC 3.1.1.4) was established in the vesicle solution of H₂O/CTAB/lecithin/heptane in this thesis. The method is preferable with high precision and less usage of sample.In the vesicle solution, the hydrolysis of phospholipase A₂ has been investigated by using egg yolk lecithin as the substrate through measurements of absorbency of the product of hydrolysis at the wavelength of 559 nm in course of reactions. The enzyme activities were dependent on temperature, substrate concentration, enzyme concentration, surfactant concentration, concentration of ion of Ca²⁺ and so on. Maximum enzyme activity was obtained at [E]=1.79umol.L^-1, [S]=20 mmol-L"', [CTAB]= 400 mmol-L^-1, [Ca²⁺]=400 mmol-L^-1, t=40°C. The lipase-catalyzed reaction obeys Michaelis-Menten kinetics in the investigated substrate concentration range (7.5-25 mmol.L^-1), and the apparent Michaelis constant K_m and the apparent maximal reaction rate V_m were determined.