CHARACTERIZATION OF THE DELTA-11-PALMITOYL-COA-DESATURASE FROM SPODOPTERA-LITTORALIS (LEPIDOPTERA, NOCTUIDAE)

One of the key enzymes involved in moth pheromone biosynthesis, palmitoyl-CoA DELTA-11-desaturase, has been characterized in subcellular fractions from pheromonal glands of adult female Spodoptera littoralis. Desaturase activity was dependent on the presence of reduced pyridine nucleotides, and NADH was a better electron donor to the enzyme than NADPH. Incubation of gland microsomes with NADPH and [C-14]palmitoyl-CoA significantly increased one unidentified reaction product. Incubation with the corresponding free acids showed the highest activity for palmitic acid followed by myristic and stearic acids. (Z)-11-Hexadecenoic acid (as the methyl ester) was identified as the only radioactive product of the main pheromonal gland desaturase by radio-GC chromatography. The optimal pH for DELTA-11-desaturase activity was between 6.8 and 7.2, and 25-degrees-C was found to be the optimum temperature for this activity. BSA, EDTA and DTT were required for maximal desaturase activity. Cyanide and azide were inhibitory, and carbon monoxide had no effect.