PURIFICATION OF A LYSOPHOSPHATIDIC ACID-HYDROLYZING LYSOPHOSPHOLIPASE FROM RAT-BRAIN

A lysosophosphatidic acid (LPA)-hydrolysing lysophospholipase was purified from rat brain and characterized. This membrane-bound lysophospholipase was solubilized by using n-octyl glucoside and purified by sequential cation, hydrophobic and gel-filtration chromatography. The purified protein has a mass of 80 kDa as assayed by SDS/PAGE. This lysophospholipase catalysed the hydrolysis of a variety of lysophosphatidic acids, but with different rates, depending on the length and degree of saturation of the sn-1 acyl group (1-oleoyl-LPA approximate to 1-stearoyl-LPA > 1-palmitoyl-LPA > 1-myristoyl-LPA). This enzyme had no measurable catalytic activity when other lysophospholipids, monoacylglycerol or phosphatidic acid were used as substrates. On the basis of its chromatographic properties, substrate specificity and cellular localization, we conclude that this lysophospholipase differs from those previously purified and speculate that it has an important function in terminating biological responses to LPA.