CATALYTIC PLASTICITY OF FATTY-ACID MODIFICATION ENZYMES UNDERLYING CHEMICAL DIVERSITY OF PLANT LIPIDS

Higher plants exhibit extensive diversity in the composition of seed s torage fatty acids. This is Largely due to the presence of various com binations of double or triple bonds and hydroxyl or epoxy groups, whic h are synthesized by a family of structurally similar enzymes. As few as four amino acid substitutions can convert an oleate 12-desaturase t o a hydroxylase and as few as six result in conversion of a hydroxylas e;to a desaturase. These results illustrate how catalytic plasticity o f these diiron enzymes has contributed to the evolution of the chemica l diversity found in higher plants.