Characteristics and biosynthesis of seed lipases in maize and other plant species

Oilseed lipases from diverse plant species exhibit differences in their substrate specificity, pH for optimal activity, reactivity toward sulfhydryl reagents, hydrophobicity and subcellular location. Seed lipase from a certain plant species is relatively specific for the native triacylglycerols or triacylglycerols containing the major fatty acids of the storage triacylglycerols of the same species. This substrate specificity can be exploited in lipid biotechnology. In most seeds, with the known exception of castor bean, lipase activities are absent in ungerminated seeds and increase in postgermination. The biosynthesis of seed lipase has been studied only in maize. The maize enzyme is synthesized on free polyribosomes in postgermination. The newly synthesized enzyme is then transferred, without apparent coor posttranslational modification, to the membrane of the lipid bodies.