title: Deamidase inactivates a D-amino acid-containing Aplysia neuropeptide.
abstract: Membrane-catalyzed degradation of the cardioexcitatory peptide, Asn-D-Trp-Phe-NH(2) (N(d)WF-NH(2)), which was previously isolated from Aplysia, was investigated in relation to its inactivation mechanism. The principal degradation was deamidation of the C-terminal amide, producing biologically inert Asn-D-Trp-Phe-OH (N(d)WF-OH). Among membrane fractions prepared from different organs, the fraction from the ganglia showed the highest specific activity of the deamidation reaction. The deamidase activity was inhibited by Ebelactone B and the serine protease inhibitor, phenylmethanesulfonyl fluoride (PMSF), while the degradation of the synthetic stereoisomer, Asn-Trp-Phe-NH(2) (N(l)WF-NH(2)), was sensitive to the divalent cation-chelating agent, o-phenanthroline, and aminopeptidase inhibitors, amastatin and bestatin. The presence of D-Trp residue in the second position of N(d)WF-NH(2) endows this peptide not only with stereospecific bioactivity but also peptidase stability. The deamidation reaction seems to be the major inactivation mechanism for this peptide.
authors.affiliation: Department of Biological Science, Faculty of Science, Hiroshima University, Higashi Hiroshima 739-8526, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Morishita
authors.forename: O
authors.initials: O
authors.lastname: Matsushima
authors.forename: Y
authors.initials: Y
authors.lastname: Furukawa
authors.forename: H
authors.initials: H
authors.lastname: Minakata
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism*; D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D001048:Aplysia; D009479:Neuropeptides / Q000037:antagonists & inhibitors* / Q000737:chemistry
chemical_list: D000596:Amino Acids; D009479:Neuropeptides; D000581:Amidohydrolases