Lysoplasmalogenase--a microsomal enzyme from rat brain.

An enzymic activity of rat brain that liberates radioactive free aldehydes from 1-[1-14C]alk-1'-enyl-sn-glycero-3-phosphoethanolamine (lyso-plasmalogen) is described. It was present mainly in microsomal fractions (crude) of brains of rats of different ages. The highest specific enzyme activity was found in 21-day-old animals. The formation of free aldehyde was dependent on the amount of enzyme protein as well as the amount of substrate added, and was linear to the incubation time up to 60 min. The pH optimum was between 7.1 and 7.3. Bivalent cations (Mg2+, Ca2+) and detergents inhibited the reaction. However, the same cell fractions as well as extracts of acetone-dried powder of brain from young or old rats possessed no enzyme activity for liberating the aldehyde from the acylated substrates: 1-[1-14C]alk-1'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine (plasmalogen) or plasmalogen of ox corpus callosum.