ISOLATION AND CHARACTERIZATION OF SINUS GLAND NEUROPEPTIDES WITH BOTHMANDIBULAR ORGAN INHIBITING AND HYPERGLYCEMIC EFFECTS FROM THE SPIDERCRAB LIBINIA-EMARGINATA

Using two-step reverse phase HPLC, we isolated and purified three pept ides with mandibular organ inhibiting hormone (MO-IH) activity from th e spider crab Libinia emarginata. One of the peptides, P22, gave a yie ld of 355 ng/SG. The others gave lower yields: P21, 9 ng/SG; P25, 67.5 ng/SG. The molecular weight was determined to be 8,439 for P25, 8,474 for P22, and 8,398 for P21 by mass spectrometry. All three peptides h ave similar amino acid compositions and contain 72-76 residues. We bel ieve these peptides to be different isoforms of one family. The MO is more sensitive to the two minor isoforms, P21 and P25. All three isofo rms can inhibit MO activity to a maximum inhibition of 70%. All three isoforms gave a significant hyperglycemic effect when injected into de -eyestalked fiddler crabs Uca pugilator. We believe the MO-IHs to be m embers of the crustacean hyperglycemic hormone (CHH) family, having si milar amino acid compositions and both biological activities. (C) 1996 Wiley-Liss, Inc.