Characterization of chromatophorotropic neuropeptides from the kuruma prawn Penaeus japonicus

Three chromatophorotropic neuropeptide hormones were purified from an aqueous extract of the sinus glands of the kuruma prawn Penaeus japonicus by two steps of reverse-phase HPLC and their amino acid sequences determined. One of them was found to show pigment concentrating activity and to have an amino acid sequence identical with that of the known red pigment concentrating hormone (RPCH), and therefore it was named Pej-RPCH. The other two peptides showed pigment dispersing hormone (PDH) activity and were named Pej-PDH-I and -II. They both consisted of 18 amino acid residues with a free amino-terminus and an amidated carboxyl-terminus, the sequences of Pej-PDH-I and -II being NSELINSLLGIPKVMTDAamide and NSELINSLLGLPKFMIDAamide, respectively. Three amino acid residues at positions 11, 14, and 16 differed between the two PDHs. Pej-PDH-II was about 5-, 7-, and 10-fold more potent than Pej-PDH-I for erythrophores, xanthophores, and melanophores, respectively. The major reason for the difference in potency between the two PDHs was attributed to differences in residues at position 16. In addition, they were found to be produced by a single individual. The order of sensitivity of the four types of chromatophores to Pej-RPCH and both PDHs was found to be erythrophores = xanthophores > melanophores > leukophores.