Purification and characterization of lysophospholipase C from pig brain

In present study, lysophospholipase C (lysoPLC) was purified from homogenate of pig brain. LysoPLC was purified from brain membranes by procedures employing acetic acid precipitation, 1-butanol solubilization and ammonium sulfate fractionation, and chromatographies. In SDS-PAGE, the purified enzyme protein was relatively homogeneous with molecular mass of around 65 kDa. The lysoPLC activity possesses an optimal pH of 8.5, and Km and Vm values of 120.3 microM, and 141.6 micromole/h/mg protein, respectively for 1-lauroyl lysophosphatidylcholine(LPC), and 72.4 microM and 89.8 micromole/h/mg protein for glycerophosphorylcholine (GPC). In thermal denaturation at 60 degrees C, the enzyme expressed the same inactivation pattern in the hydrolysis of 1-lauroyl LPC and GPC. In the structure activity relationship, catalytic efficacy (Vm/Km value) was the greatest for 1-docosahexaenoyl LPC, followed by 1-arachidonoyl LPC, GPC, 1-hexanoyl LPC, 1-lauroyl LPC, 1-linoleoyl LPC, 1-myristoyl LPC and 1-oleoyl LPC. Metal ion requirement indicates that Zn(2+) was crucial for lysoPLC activity. Noteworthy, in the inhibition by oxyanions, the enzyme was selectively and noncompetitively inhibited by tellurite ions with Ki value of 0.16 and 0.18 microM in hydrolyzing 1-lauroyl LPC and GPC, respectively. Taken together, it is suggested that lysoPLC, possessing broad substrate specificity, may be implicated in the supply of phosphocholine in brain tissue.