In vitro metabolism of an insect neuropeptide by neural membrane preparations from Lymantria dispar.

Neural membrane fractions, prepared from brain-subesophageal ganglion complexes of the adult lepidopteran Lymantria dispar, contain at least two peptidases capable of metabolizing locust adipokinetic hormone-I in vitro. The initial fragments, pGlu1-Leu2-Asn3 and Phe4-Thr5-Pro6-Asn7-Trp8-Gly9-Thr10, result from the action of an endopeptidase with properties similar to those reported for neutral metalloendopeptidase in Schistocerca gregaria and mammalian endopeptidase 24.11. The heptapeptide is further degraded by an aminopeptidase that exhibits kinetic properties similar to those described for aminopeptidase 3.4.11.2. These enzymes appear to be responsible for the first two steps in AKH catabolism in L. dispar.