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

One of the key enzymes involved in moth pheromone biosynthesis, palmit oyl-CoA DELTA-11-desaturase, has been characterized in subcellular fra ctions from pheromonal glands of adult female Spodoptera littoralis. D esaturase activity was dependent on the presence of reduced pyridine n ucleotides, and NADH was a better electron donor to the enzyme than NA DPH. 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 pal mitic acid followed by myristic and stearic acids. (Z)-11-Hexadecenoic acid (as the methyl ester) was identified as the only radioactive pro duct of the main pheromonal gland desaturase by radio-GC chromatograph y. 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 thi s activity. BSA, EDTA and DTT were required for maximal desaturase act ivity. Cyanide and azide were inhibitory, and carbon monoxide had no e ffect.